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  1. Fifth Wheel King Pin
  2. CURT
  3. Lippert 1621
  4. 18000 lbs GTW
  5. Absorbs Road Shock and Reduces Chucking
  6. Upgraded Pin Box
Curt Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs

Curt Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs

Item # LC328492
Our Price: $1,538.49
You Save: $478.23
Fifth Wheel King Pin
This item qualifies for Free Truck Freight Shipping
Shipping Weight: 232 lbs
In Stock
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Product Expert Kathleen M

Is this right for you? Product Expert Kathleen M says:

Yes, if you:

  • Have heard of the AirRide and want that premium experience but with some added support to dampen any chucking
  • Often drive over very rough roads and want to save your truck and trailer (and yourself!) from getting beat up by all the bumps and dips

No, if you:

  • Get annoyed by having one more thing to check before hitting the road - the air pressure on this needs to be monitored and adjusted
  • Use a gooseneck adapter to tow your fifth wheel
  • Have a trailer that weighs over 20,000 lbs
Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 1621 pin boxes. 1-636-306-4830 to order CURT fifth wheel king pin part number LC328492 or order online at Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs. Fifth Wheel King Pin reviews from real customers.
  • All Info
  • Reviews (127)
  • Q & A (0)
  • Photos
  • Why etrailer?

CURT Fifth Wheel King Pin - LC328492

  • Lippert 1621
  • 18000 lbs GTW
  • Absorbs Road Shock and Reduces Chucking
  • CURT
  • Upgraded Pin Box
  • Fixed Turret

Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 1621 pin boxes.


  • Air ride pin box with a pivoting head replaces standard pin box on your 5th-wheel trailer to cushion your ride, improve handling, and limit strain on truck and trailer
    • Drastically reduces chucking
    • Virtually eliminates bounce and jarring
  • Internal air bag absorbs road shock
    • Scissor-like motion allows pin box to compress, compensating for jarring and bounce
    • Built-in shock ensures that pin box rebounds - keeps air bag from breaking down
  • Pivoting head limits chucking by allowing controlled movement of the king pin within your hitch
  • Rubber compound built into the head absorbs road shock
    • Reduces wear and tear on trailer
  • Black powder coat provides rust resistance
  • Sturdy steel construction
  • King pin connects to any 5th-wheel trailer hitch
  • Bolt-on installation with no assembly required
  • Made in the USA


  • Designed to replace Lippert 1621 5th-wheel pin box
  • Weight capacity: 18,000 lbs
  • 1-Year limited warranty


  • Do not use the Curt Flex Air pin box with any type of gooseneck adapter.

Getting there is half the fun, right? Not if you're being bumped, jerked, jammed, and pushed around from the chucking, road shock, and bounce that occurs as you tow your fifth-wheel trailer or RV. And imagine the costly wear and tear on your trailer as it endures that rocky ride.

Put the fun back into your trip and ease the stress on your trailer by replacing your factory pin box with the Curt Flex Air pin box. The internal air bag and built-in shock work together to cushion your ride, improve handling, and limit strain on both your truck and your trailer. But what sets the Flex Air apart from other air ride pin boxes is the addition of a pivoting head. This head, along with its built-in rubber compound, provides additional cushion, absorbs road shock, and reduces chucking for a significantly improved ride.

Rubber Compound and Internal Air Bag Absorb Road Shock

Curt Flex Air pin box has a rubberized pivoting head

A heavy-duty rubber compound is built into the head assembly of the Flex Air pin box. This rubber is the first defense against road shock. It helps to absorb the bumps and vibrations experienced when towing a fifth-wheel trailer over rough roads. Standard pin boxes without any type of shock absorption transfer road shock to your trailer, resulting in potential damage to the trailer and an overall bumpy ride. The shock-absorbing rubber inside the Flex Air takes the beating so there's less wear and tear on your trailer or RV and you get a smoother ride.

Curt Flex Air pin box has a shock and air bag

Because the rubber may not be able to absorb all of the road shock that you experience, the Flex Air also implements air ride technology to virtually eliminate shock. When you encounter uneven terrain on your trip or hit a pothole on the highway, the Flex Air pin box compresses vertically, similar to how a pair of scissor blades closes in on each other. This compression transfers the road shock and vibrations to the internal air bag, saving your fifth-wheel hitch, trailer, and tow vehicle frame from enduring a rocky ride.

A built-in strut, or shock, controls the Flex Air's compression so that the internal air bag doesn't burst. The strut also causes the pin box to appropriately rebound without any bounce, and positions it to be ready for the next bump in the road.

Pivoting Head Reduces Chucking

Lippert Flex Air pin box has a pivoting head that reduces chucking

The pivoting head on Flex Air allows for controlled back and forth movement of the king pin to reduce the uncomfortable jarring known as chucking. Unlike a rigid pin box that has little give at the point where the trailer and the hitch are connected, the Flex Air can pivot slightly to compensate for those times that your trailer suddenly pushes or pulls on your tow vehicle. Because the pin box head - not the king pin itself - is moving, the chucking that often occurs when the king pin jerks around inside the hitch is significantly reduced.

Simple Setup and Installation

First, simply remove your existing Lippert 1621 pin box from your trailer. The Flex Air uses the same bolts that held on your original pin box so no additional hardware is required for installation. Plus, the Flex Air pin box comes out of the box ready to be put on your trailer, so no assembly is needed. Because the Flex Air is quite heavy, you should put it on an elevated surface or have a friend help you support its weight during installation.

The internal air bag should be inflated after the Flex Air pin box has been mounted on your trailer. Using the air intake valve, inflate the air bag until the outer cylinder of the shock rises high enough to fully expose the yellow inflation indicator sticker.

328492 Curt Flexair Fifth Wheel Kingpin Box for Lippert 1621

Replaces 328492 Lippert Components (LCI) Flexair by Trail Air Fifth Wheel Kingpin Box for Lippert 1621

Installation Details LC328492 Installation instructions

Customer Satisfaction Score:

Customer Reviews

Curt Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs - LC328492

Average Customer Rating:  4.6 out of 5 stars   (127 Customer Reviews)

Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 1621 pin boxes.


I bought the Flex Air to replace the standard Lippert pin box on our Cedar Creek fifth wheel that weighs 12K lbs. Just looking for something to smooth out the ride and the Flex Air seemed to have good reviews and recommendations.

I went to the Lippert website to download the installation instructions because I couldn't get the link on the etrailer website to work. The instructions will give you the torque values required for installation and the air pressure for the inflatable airbag on the hitch.

Installation was straight forward, but you better have a plan because this thing is heavy (300 lbs) and it will take some manpower to move around and install.

Really glad we switched out pin boxes, the Flex Air was a great choice and definitely smoothed out the ride.
Joel - 02/13/2021
Really glad we switched out pin boxes, the Flex Air was a great choice and definitely smoothed out the ride.
Joel - 02/13/2021


This is the best money I have spent on my camper hands down. My hitch weight is a bit over 3200 lbs. I use a PullRite Super Lite hitch, photo attached. Once locked on the king pin, four bolts are set from the adapter plate against the king pin plate. The plate on the Flex Air is twice as thick as the original pin box and I have way more confidence in a solid set of these four bolts. I was blown away by how this hitch absorbed road shock. I will never have another 5th wheel without this set up.

Since this original post I have gone back to a regular style 5th wheel hitch new truck with factory puck system but the Flex Air is still doing its thing and I will never pull a trailer without it unless something better is invented.
Russ - 02/11/2021


Item was as described and has made a huge difference in the overall ride of m truck and 5th wheel.

Thank you very much for the timely delivery although the lift gate on the delivery truck did not work so we needed to slide it down some 2x8's I had on to the back of my truck. All good the driver was a great help.


4 stars as I have just recently installed this although I received it over a year ago.
I just put 750 miles on it and experienced almost every PAVED road condition imaginable and it worked great. I can't imagine what that would have been like with the stock pin box.

4 stars because I still need to see how it performs off road and I am just a few days into using it on a trip covering OR, ID, MT and WY so I still have my personal evaluation to complete and need more drive time to see if anything fails on it.

Installation was a breeze but it's a heavy hitch so caution is advised.

I just finished a 3,000 mile trip from Oregon to South Dakota. The hitch works like a dream. Very few road issues are transferred to my truck from the trailer. This is a great hitch. Totally satisfied with this purchase.If anything I wish they made an offset pin box so that I could adjust it to make my trailer ride correctly, as it is with my 4x4 it runs a tad nose high.
Arman K - 10/08/2019


Purchased another 5th wheel trailer that had original solid pin box. I had a 5th air born pin box that I did not keep. New trailer is much heaver so up graded to Flex Air pin box. Very happy with new pin box.


First, about etrailer. As always, their service was outstanding. They honored their low price guarantee without question and shipping was fast.
I upgraded from a Trailair Air Ride pin box with a fixed turret. That pin box helped with bouncing and jarring, but I still got a lot of "chucking". This FlexAir pin box solved that problem as well. Installation was a breeze, although you must make sure you have enough adjustment on your trailer to mount this pin box higher up than your existing pin box. I had to mount it at the very highest set of holes on my trailer. Lipperts web site has specs on this pin box and installation instructions, including measurements and torque specs. With the help of a friend and using the bed of my pickup truck, we unbolted the old one and bolted the new one in. Took about an hour and that was not hurrying.
I took the trailer out this past weekend with the new pin box and hit some pretty bad roads. Wow! What a difference this pin box makes. I can only describe the ride one way. Smooooooth. I am very pleased with both etrailer and this product. It's pricey, but to me, pulling a large fifth wheel trailer, it's worth every penny. Highly recommended.


Install went pretty smooth. Did it from the bed of the truck, using a motorcycle jack in front and a small hydraulic in back. Make sure your torque wrench can dial to 160 ftlbs. I will update after I tow it!!!

I cannot believe it has been a year....and a trip to Perdido Key, FL and Breckenrigde CO. In addition to taking care of us, I have to tell you, it will take care of your trailer too! Improved our towing experience old pin box was an upgrade Rotoflex greatly. Worth every penny! If you did not see my earlier post, my friend and I installed it ourselves. Motorcycle jack in the back of a pick up bed. :
James J - 02/05/2020


Have not had a chance to take it for a road test yet. But it fit well, was easy to mount, the issue I ran into was getting the pin height. As my truck is 4x4, and the B&W hitch is as low as it can go, I still needed another 2 inches to get the pin box high enough, could not raise pin box any higher, and with the 5th wheel already at 13'4" did not want to lift the trailer, so ended up lowering the truck 2 inches to get everything back level again. But will find out next week how it works as we start out on a close to 12,000 mile trip to the west coast and back across through canada and back to florida.


I have used my Flex Air for over one year and put around 3000 miles on it. I purchased this for one reason to reduce bucking when I it bumps in the road. I can safely say that it has virtually eliminated the bucking. It has also made the ride a lot smoother. I would highly recommend the Flex air. I did my own install of this product by my self.

My rig
2018 Toyota Tundra with a Husky 16 KW Hitch
2017 KZ Durango 30 ft.


I will be on the third flexair pin box when it gets here on the 21st of November 2016. The problem iIm having is with the lower roto flex portion. The rubber block shifts and I have talked to others with the same problem. Lippert has been great about the replacement, But the the hassle of replacing this three times in one year is not worth it.


It’s a well built unit and helps the ride quite a bit. I was hoping it would completely stop the chucking. It takes a lot of it away but there is still some.
Would purchase one again.


Best thing since slice bread,the way the roads are not repaired and full of pot holes and patches this has smooth out the ride, A must to have on your 5th wheel,,


Reflection 320MKS
Dealing with etrailer
was very easy. Starting with getting the correct information on which pin box would be suitable for our trailer.
The unit arrived in 10 days from ordering it. Which was less than the estimated timeframe when placing the order.

The only down side, on inspection when arrived, the air bag valve was damaged in transit. A quick email with photos, a call to etrailer & they have a replacement part ready to dispatch.
Great customer service & i would definitely recommend them.


Product arrived in a timely fashion in an un damage condition. Quality was better than expected. Installation for me took about two hrs, with my wife helping. I placed the pin box in the bed of my truck with the help of a frontend loader and let it down on a floor jack. From there install was fairly easy.

Pros: Good quality Heavy Duty

Cons: You will need 3 or 4 strong friends to handle it
No instructions included I did find a pdf on the bottom of the page however that listed the torque for 1/2" bolts

Works great after a year of use preforms well. I haven’t had to put air after the initial start up.
Paul` - 08/28/2021


Great Product !!!!


1st off, Tammie from follows up with a 1year review of this product! Great way to stay ahead of the game. GO ETRAILER!!. And oh by the way.....The new pin box smoothed out the ride and handling nicely. Definitely happy I bought it.


Dealing with you guys and your suppliers ment all kinds of information going in different directions and nothing ever jiving. Worst experience I've ever had with your delivery companies. Making promises never fulfilling them never calling ahead of time me having to chase them down when you chase him down you talk to somebody that is in the orient. They say will have someone call you in 1 hour. Never did they ever call back. I'll just stop is here because I don't want to get angry it's too upsetting. Finally got delivery 5 days after it was supposed to be here 3 days waiting all day long as promised and nobody showed up when you call back they say will have someone call you in an hour. They still have not called driver showed up here finally 5 days late said he didn't have my number you're the reason I know that it would be was here cuz he had a 40 ft tractor trailer


Awesome price! Being installed on a Grand Design 375RES. Shipment went great this is a heavy unit, arrived banded on pallets in excellent condition. Installation was simple and as instructions stated. Waiting for the next road trip to be able to test effectiveness. Always been a pleasure dealing with E-Trailer.


Love it! Makes the ride so much better and safer especially when you cross those roller-coaster bridges that will nearly bounce the rear tires off the ground without this hitch. Only complaint is that I have to add air if it sets for a couple weeks.


I can’t rate this product as we have yet to install it on our trailer. The pin box dimensions aren’t what is specified in description. The opening to mount the pin box is 12” on our trailer and the Curt Flex air that we received is 11 3/4”. We have talked to Lippert and etrailer and have gotten mixed answers about the safety of mounting a product that is off by 1/4” on to a 16,500 lb trailer.


The FlexAir pin box has been great. The ride while pulling our Laredo 5th wheel is much smoother. Traveling is much more pleasurable. I especially appreciate the follow up from etrailer.


This 250 lb item was shipped in a cardboard box that was just sitting on a pallet. When I opened the box I found the Flex Air was sitting upside down with the foam pad on top. I have no idea how the air filling nozzle wasn't damaged. Luck I guess. There were no "UP" markings on the box. No instructions were included.
Installation went smooth, it's just heavy so be careful. Instructions and videos can be found on-line.
The Flex Air is at least 4" taller than the OEM box that came with our Grand Design Reflection. I mounted the Flex Air as high as I could and lowered the receiver on the truck. The trailer is still nose high but seems to tow fine. My test ride was noticeably smoother. You can see a lot of motion on the Flex Air that would have otherwise been transferred to the truck.

Fifth Wheel tows smooth. After 5000 miles from Minnesota to the south east US. Freeway and bumpy back roads. Wind gusts up to 25 mph. The trailer tows smooth. No chucking. The trailer is still higher in the front but it has no noticeable effect on towing and the leaf spring suspension can handle it. The tires seem to be equally loaded, no uneven wear.
Steve t - 11/04/2020


Excellent product,well built. I ordered it online and it was delivered within 3 days, no complaints!!


Really helped take away most of the jerky ride we used to get from our solid king pin. The air bag helps to smooths out rough roads. As per the advice of Lippert customer service I made 5 pound adjustments until I found the best ride. I keep a portable battery operated air pump along for adjustments. My airbag had a small air leak at the valve threads when new. After resealing the threads all is good.

Still working great. The smooth ride makes towing much more enjoyable.
Wesley - 05/28/2019


Excellent product although we haven;t yet installed it due to the manufacturer torquing the mounting bolts on our original pin box so tightly that I can't get them off. That is no knock on this product. I will be taking it to a dealer for mounting.

I will followup for more comments when it's mounted next week.

Looking forward to the promised smoother ride.

The product arrived quickly and in good condition.

Fantastic King Pin. It has made a huge difference in our comfort and reduced driver fatigue when pulling the 5th wheel. Nearly no chucking except when bad drivers cut us off forcing a hard break and no porposing of the trailer and truck. Sometimes the ride is so smooth we forget we have a very heavy 5th wheel back there.
Eric - 03/23/2021

Show More Reviews

See what our Experts say about this CURT Fifth Wheel King Pin

  • Can a Pullrite Slider Hitch be Used with a Trailair Flexair
    PullRite Slider Hitches can be used with the Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced. All you need is the correct capture plate but you can get that from Pullrite. It should be part number PR_331756 or PR_331760.
    view full answer...
  • Can the Rubber Parts of Lippert Flex Air Replacement Pin Boxes be Replaced
    It sounds like you are talking about the air bag that is in the front of the Flex Air pin boxes, such as # LC328492, or the rectangular rubber piece inside. If you need to replace the air bag I would need to know which model Flex Air that you have. If the bag is not holding air then it is likely the Schrader valve and not the bag itself. If you are talking about the rectangular rubber compound on the inside it too could be replaced. When Lippert was here recently to provide product training...
    view full answer...
  • King Pin to Bolt Hole Rows on Lippert Flex Air Pin Box for 1621 5th Trailer Pin Boxes
    The pin box used on a 5th wheel trailer is chosen based on several factors. If you used a pin box that is too much longer than what it was built with it could put too much stress on the frame. On the Lippert 1621 the center of king pin to front row of bolt holes is approximately 17-3/4 inches and to the back row approximately 25-5/8 inches. The aftermarket box # LC328492 will be approximately 3 inches longer which would be fine.
    view full answer...
  • Is Lippert FlexAir Pin Box Better Than Their Tri-Glide
    I spoke to my Lippert representative who tells me that the ride quality provided by the FlexAir Pin box will be superior to that of their Tri-Glide, which worked very well. We do carry the FlexAir that's a replacement for the Lippert 1621, the part number would be # LC328492. You have a quality hitch, once you add an air ride pin box, you'll be surprised by how much your ride improves.
    view full answer...
  • Cushioned Pin Box Recommendation for a 2015 Grand Designs Momentum 328M
    Yes, the Trailair Flex Air 5th Wheel Pin Box # LC328492 will fit as a replacement for your Lippert 1621HD pin box. The dimensions of this will be slightly different. The king pin will stick out an additional 3.39 inches and will sit lower (causing the trailer to sit up higher), about 1.5- 2 inches. There is an additional set of install holes on this pin box to accommodate for the height difference that is due to the air bag. This pin box does have an 18k capacity like what the 1621HD has...
    view full answer...
  • Can You Hook Up a 5th Wheel Trailer at an Angle Using a Trailair Air Ride Pin Box
    Trailair Flex Air 5th Wheel Pin Box # LC328492 for Lippert 1621 pin boxes will work the same hookup angles that your 5th wheel hitch is rated for which is to say as straight of an angle as you can get. The pin box needs to be able to ramp up the 5th wheel hitch so the king pin gets funneled into the hitch jaws. I advise using a great deal of caution and a spotter if there is any doubt about the angle of approach.
    view full answer...
  • Is Ride Quality Better Using a Flex Air Pin Box Over a 5th Airborne Pin Box
    The Flex Air 5th wheel trailer pin box, # LC328492, for Lippert 1621 pin boxes has an extra element to improve ride quality not found on the 5th Airborne pin boxes. In addition to the air bag and shock the skid plate can also pivot. Some movements of the trailer will therefore not be transferred to the hitch or not as severely resulting in a more enjoyable tow.
    view full answer...
  • Recommended Replacement Pin Box for 2015 Keystone Cougar 313 with Lippert 1621 Pin Box
    You are correct that an upgraded pin box can help dramatically improve your truck and trailer's ride when towing. The Trailair pin boxes offer great options for you. The upgraded pin box I recommend to replace your existing Lippert 1621 pin box is the Trailair Flex Air 5th Wheel Pin Box # LC328492. This pin box features an air bag and shock that will absorb road shock to help minimize jarring and bounce, while the pivoting head on the pin box helps limit chucking. The airbag, shock, and...
    view full answer...
  • Heavier-Duty Replacement Pin Box For 2013 keystone Alpine 3535e Fifth Wheel Trailer
    We do offer several pin boxes that have more weight capacity than the 16,000-lb you said you have on your Keystone. The first thing we need to know is what model pin box will fit your trailer. Since you said you have a Trailair installed, you can let me know what model it is and I will be happy to find a replacement that has more capacity. That way we will match the mounting bolt pattern for your trailer. Most of the time it is found on the driver side of the pin box on a plate or sticker....
    view full answer...
  • How to Pick Out a Replacement Pin Box for a Trailer
    Sounds like you are looking for a cushioned replacement pin box for your trailer. We most likely have what you are looking for, but you are going to have to determine what pin box model and number you have. I tried looking it up online and couldn't find anything. Up near the pin box there should be a plate or sticker that will have this information. A very popular pin box is the Lippert 1621 which is what the part # LC328492 that you referenced is designed to fit. If you have something...
    view full answer...
  • Can Air Pressure of a Trail Air Pin Box be Lowered to Level Fifth Wheel Trailer
    Ideally you would lower the head of your fifth wheel hitch to bring down the nose of the trailer so that it sits level. You really want to keep the proper amount of air pressure in the Flex Air part # LC328492 that you referenced and it is not designed for air pressure to be a leveling device. As long as you keep at least 6 inches between the bed rails of your truck and the trailer overhang lowering the head of your fifth wheel hitch would be the best solution. Most heads have around 4...
    view full answer...
  • Fifth Wheel Pin Box Upgrade Recommendations for a Trailer with a Lippert 1621 Pin Box
    If your 2014 345 Open Range Fifth Wheel Trailer has a Lippert 1621 pin box the Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced would be an excellent option. The only option I would recommend over this would be for if you have a short bed truck. Then I would recommend the cushioned Sidewinder part # RP61422 that will give you the turning clearance your trailer would need to make tight turns without having to use a slider hitch. To determine what pin box you have you...
    view full answer...
  • Flexair Pin Box Length and Height for Lippert 1621
    I spoke with my contact at Lippert and although she wasn't able to provide me with the center of the king pin to first hole measurement, I do have the back of the mounting plate to center of the king pin measurement for you for the # LC328492. That dimension is 29-9/16 inches. The overall height from the top of the mounting bracket to the bottom of the king pin is 19-9/16 inches.
    view full answer...
  • TrailAir Flex Air Pin Box Recommendation to Replace Worn Out Tri-Glide
    You are going to need to replace the entire pin box. The Tri-Glide was notorious for needing quite a bit of maintenance with the rollers and even if kept up can still wear out. That is part of the reason why it was replaced with the Flex Air. The Flex Air # LC328492 that you referenced will fit your trailer and will work just as well as the Tri-Glide in terms of cushioning the ride and due to it's design will not require the same amount of maintenance.
    view full answer...
  • Cushioned Pin Box Recommendation for a Lippert 1621 Pin Box on a Cougar 29RET Xlite
    For a cushioned pin box to replace your Lippert 1621 the TrailAir Flex Air part # LC328492 would be a great option. This is made by Lippert will help with both vertical and longitudal chucking. With this pin box the overall height from the top of the mounting bracket to the bottom of the king pin is 19-9/16 inches. You would need to compare that to what you currently have, but typically when the pin box is inflated to the recommended air pressure it will be a couple inches higher. You...
    view full answer...
  • Will Adding a Flex Air Pin Box Increase the Pin Weight on a 5th Wheel Trailer
    No, you would not HAVE to factor in the weight difference between the Flex Air pin box # LC328492 and the factory pin box though you can if you want to and it would be more accurate. But a weight difference of around 100 pounds is not significant in 5th wheel towing (the standard Lippert 1621 pin box is about 100 pounds and the Flex Air is a little over 200 itself). I don't disagree with your pin weight assessment except that the trailer manufacturers will say what it should be. That usually...
    view full answer...
  • How to Pick Out a Trail Air Pin Box for a 2015 Jayco Fifth Wheel Trailer
    Most of the Jayco fifth wheel trailers have the Lippert 1621 pin box like what the Trailair part # LC328492 is designed to replace so most likely this will fit and work great as a way to cushion the ride of your fifth wheel trailer, but you will need to verify that you have a Lippert 1621 pin box on your trailer first. There should be a sticker or a stamping on the OEM pin box of the trailer that will list the number pin box that is on the trailer. The Lippert 1621 is one of the most popular...
    view full answer...
  • How to Pick Out a Trailair Pin Box for a Primetime Crusader 315RST
    You will need to determine which pin box you have on your trailer before you can pick out the correct Trailair pin box. The part # LC328492 fits the Lippert 1621 pin box which is very popular and is most likely on your trailer but you need to verify this first. Up near the pin box there will be a plate or sticker that has the pin box info listed. If you do not have a 1621 check out the link I attached that has all of the pin boxes we offer. You will need to select your pin box from the...
    view full answer...
  • Will King Pin Height Remain The Same When Replacing 1621 Pin Box With Trailair Flex Air Pin Box
    I called my contact at Lippert and asked about the Trailair Flex Air 5th Wheel Pin Box, part # LC328492. My contact at Lippert said that if you match the same mounting bolt pattern you have on your existing 1621 pin box, the king pin height on the Flex Air will be at the same height so you will be good to go.
    view full answer...
  • How Many Bolts are Required to Install the Trailair FlexAir Pin Box on a Trailer
    When installed the Trailair Flex Air 5th Wheel Pin Box # LC328492 only requires 4 bolts to be ran through the pin box and the trailer frame. I attached a picture that shows this pin box installed on a similar trailer and that it only uses 4 bolts. So if you can secure the pin box at the height you need with 4 bolts you would be just fine.
    view full answer...
    Image 1 for
  • Can an Air Ride Pin Box be Used with Air Bag Suspension Enhancement Installed on Truck
    Air suspension enhancement can work fine with a cushioned air-ride pin box. The two systems would be totally fine together. What you might be thinking of is that it isn't recommended to run a cushioned fifth wheel to gooseneck adapter with a cushioned pin box on a trailer. If your trailer has a Lippert 1621 pin box on it currently the Trailair Flex Air part # LC328492 that you referenced would fit it and work well to provide you with a smoother ride quality. The Flex Air pin boxes are...
    view full answer...
  • How to Pick Out Cushioned Pin Box for a 2009 Big Horn Fifth Wheel
    I would need to know what pin box you have on your trailer to pick out the cushioned pin box that would fit your trailer. Check the plate or sticker near the top of the pin box to see what you have so that we can pick out the correct pin box. There will be a model number and brand like Lippert 1621. With that info you can check out the link I attached that has all of the pin box replacements we offer. You will be able to then select your pin box from the filters to see which cushioned...
    view full answer...
  • Will a Capture Plate for a PullRite SuperGlide Fit the Flex Air Pin Boxes
    We do not sell the capture plate you need but it is 331761. That is the model indicated by PullRite that fits the Flex Air pin boxes such as # LC328492.
    view full answer...
  • Can Trailair Flexair Pin Box be Used with Grand Design Solitude 360R Fifth Wheel
    PullRite Slider Hitches can be used with the Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced. All you need is the correct capture plate but you can get that from Pullrite. It should be part number PR_331756 or PR_331760. Your Grand Design Solitude 360R has a Lippert 1621 like what this is designed to fit.
    view full answer...

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    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate fifth wheel king pin information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee John H
Expert Research:
John H
Employee Adam R
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Adam R
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Kathleen M
Updated by:
Kathleen M
Employee Shelly K
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Shelly K
Employee Wilson B
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Wilson B
Employee Hannah L
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Hannah L
Employee Mike S
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Mike S
Employee Isabelle B
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Isabelle B
Employee Noah M
Updated by:
Noah M
Employee Manda E
Updated by:
Manda E
Employee Dustin K
Video Edited:
Dustin K
Employee Chelsea B
Written by:
Chelsea B
Employee Jonathan Y
Video by:
Jonathan Y
Employee Conner L
Test Fit:
Conner L
Employee Michael B
Installed by:
Michael B

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

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