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Underbed Rail and Installation Kit for Demco UMS 5th Wheel and Gooseneck Trailer Hitches

Underbed Rail and Installation Kit for Demco UMS 5th Wheel and Gooseneck Trailer Hitches

Item # DM8551004
Our Price: $435.51
Fifth Wheel Installation Kit

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Custom, underbed rail kit allows for uninhibited use of your truck bed once your hitch is removed. Works with Underbed Mount Series (UMS) fifth-wheel and gooseneck hitches. 1-800-940-8924 to order Demco fifth wheel installation kit part number DM8551004 or order online at Free expert support on all Demco products. Great prices and Fastest Shipping for Underbed Rail and Installation Kit for Demco UMS 5th Wheel and Gooseneck Trailer Hitches. Fifth Wheel Installation Kit reviews from real customers.
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2004 GMC Sierra - Underbed Rail and Installation Kit for Demco UMS 5th Wheel and Gooseneck Trailer Hitches

  • Below the Bed
  • Custom
  • Demco

Custom, underbed rail kit allows for uninhibited use of your truck bed once your hitch is removed. Works with Underbed Mount Series (UMS) fifth-wheel and gooseneck hitches.


  • Installation kit is designed for use with Demco UMS 5th-wheel and gooseneck trailer hitches
  • Underbed rails allow for complete access to truck bed when hitch is removed
    • No exposed rails
    • 4 Mounting holes sit flush with truck bed
  • Vehicle-specific design reduces installation time and requires less drilling than universal systems
    • Brackets mount to the outside of your truck's frame rails - drilling is required
    • Crossmembers sit along top of frame rails, beneath bed
  • Sturdy, black powder coated steel resists corrosion
  • Rails and installation hardware included
  • Made in the USA


  • Application: Demco Underbed Mount Series (UMS) 5th-wheel and gooseneck trailer hitches
  • 5-Year limited warranty

8551004 Demco Hijacker UMS Under Bed Rail Frame Bracket Kit

Installation Details DM8551004 Installation instructions

Customer Satisfaction Score:

Customer Reviews

Underbed Rail and Installation Kit for Demco UMS 5th Wheel and Gooseneck Trailer Hitches - DM8551004

Average Customer Rating:  5.0 out of 5 stars   (6 Customer Reviews)

Custom, underbed rail kit allows for uninhibited use of your truck bed once your hitch is removed. Works with Underbed Mount Series (UMS) fifth-wheel and gooseneck hitches.

Chevrolet Silverado

2003 Chevrolet Silverado 2500HD 4x4 extended bed Duramax


Great product easy to install.


Easy installation


The experience overall was good. Shipped in a timely manor and product was as shown. No complaints and would purchase from them again in the future.


easy to install good prouduct



See what our Experts say about this Demco Fifth Wheel Installation Kit

  • How to Install the Underbed Rail and Installation Kit for Demco Hijacker 2005 GMC Sierra 3500
    I can walk you through the installation of the Underbed Rail and Installation Kit for Demco Hijacker UMS 5th Wheel and Gooseneck Trailer Hitches part # DM8551004 but we have not had the chance to install this on a 2005 GMC Sierra 3500 yet. A standard hand drill can be used to drill the holes through the frame rail. On some models there will be a heat shield that is attached to the bottom of the truck box that will have to have a section of it removed to make clearance for the base rail(s). 1....
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  • Will Demco Hijacker Rail Kit Fit Truck with BedRug Installed in Bed
    You would have to cut out slots in the Bedrug to give access to the Demco Hijacker Rail Kit # DM8551004 rail kit of your truck. We spoke with our contact at Bedrug to confirm that this is the recommended method for this.
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  • What are the Installation Instructions for the Demco Underbed Rail and Installation Kit # DM8551004?
    Yes! I went ahead and attached the installation instructions of the Demco Underbed Rail and Installation Kit # DM8551004 (Demco part 8551004) to this answer.
    view full answer...
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  • Lowest Height of Demco Hijacker on 2002 GMC Sierra 2500HD
    The lowest height setting of the Demco Hijacker Autoslide Fifth Wheel Hitch # DM8550022 is 15-1/2". Since you will be using the Underbed Rail and Installation Kit # DM8551004 in your 2002 GMC Sierra 2500HD there will be no additional height added.
    view full answer...
  • Demco Hijacker Autoslide Hitch and Rail Kit Recommendation for 2005 Chevy Silverado 2500HD Short Bed
    We have just what you would need. The Demco Auto Slide you would want is the part # DM8550022 which will fit the underbed Demco rails part # DM8551004 that are custom fit for your 2005 Chevy Silverado 2500HD short bed.
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  • Brake Controller Relocation Kit Needed for 2008 Chevrolet Silverado Installing Demco Underbed Rail
    I spoke with Demco and they do not currently have a solution for this issue. The only relocation kit we offer for your 2008 Chevrolet Silverado's factory trailer brake controller is the Factory Brake Controller Relocation Kit for Fifth Wheel and Gooseneck Rails # 58318. This kit works as a spacer to move the factory brake controller away from the frame in order to install the 5th wheel brackets. My contact at Draw-Tite confirmed that it will move the brake controller approximately 3/8 of...
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  • Can I Use An Auto-Slide Hitch If I Have a B&W Turnoverball Gooseneck Trailer Hitch Installed
    I have two options for you but there is no way to use an auto-sliding 5th wheel hitch with the B&W Turnoverball Underbed Gooseneck Trailer Hitch installed because there is no room for anything else to mount and you can't use an adapter because of the singular connection point and its inability to withstand the added torque for the auto-sliding 5th wheel hitch. Therefore, you can either use the B&W Companion Slider Gooseneck-to-5th-Wheel Trailer Hitch Adapter part # BWRVK3400 or you will...
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  • Recommendation for a 5th Wheel Hitch on a 2008 Chevrolet Silverado 2500
    We highly recommend using a sliding hitch for the short bed trucks so that your trailer will not make contact with the back of your truck while towing. These hitches allow you to make tight turns on campgrounds or parking lots without damaging your vehicle. It's important to note that it is not recommended to tow with it in the extended/turning position but only in the towing position. For your 2008 Chevrolet Silverado 2500, we offer custom fit brackets for your specific truck that I...
    view full answer...
  • Will Demco Underbed Base Rails & Autoslide 5th Wheel Fit 2001 Chevy Silverado 3500 Long Bed
    Your 2001 Chevy Silverado 3500 with an 8 foot bed will be able to utilize the Demco underbed base rails along with the Autoslide hitch; the part number for the base rails is the following: - Underbed Rail and Installation Kit # DM8551004 This will work with the Demco Hijacker Autoslide 5th Wheel Trailer Hitch w/ Slider - Underbed # DM8550022. That part is the combination of the Replacement Head and Base Assembly for Demco Hijacker Autoslide 5th Wheel Trailer Hitches # DM6077 and the...
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  • Can Curt Fifth Wheel Hitch Fit in Place of Demco Hijacker for 2007 Chevy Silverado
    For your 2007 Chevy Silverado 2500HD Demco has two styles of rail kits available. There an underbed version and an above bed version which is much more popular and most likely what you have. The kit you'd have for your truck would be the part # DM8552009-71 which you can look at to get an idea and compare to what you have. If what you have looks like this then yes a Curt E16 hitch # C16115 would work as it is designed to fit the same rails. If it's an underbed rail kit it would be part...
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  • Demco Hijacker Fifth Wheel Hitch or Reese Elite Slider Recommendation for 2010 GMC Sierra Short Bed
    I have a great solution for you. Since you are looking for an under-bed rail system that will leave your truck bed empty when the hitch is removed I would recommend you go with the Demco Hijacker hitch part # DM8550022 and underbed rail kit part # DM8551004. Since you have a short bed you will need a hitch that has a slider so that you can have enough clearance to make tight turns. The Reese Elite Slider hitch part # RP30144 and Rail Kit part # RP30061 is a GREAT option, but this setup...
    view full answer...
  • Slider Hitch Recommendation for 2005 Chevy Silverado 2500HD with 6-1/2 foot bed
    First thing you should note is that it can be pretty difficult to tow a fifth wheel trailer with a truck that has been lifted, especially one that has as big of tires and lift as yours. The reason is that you have to tow the trailer level and you also have to have 4-6 inches of clearance between the bed rails of the truck and the over hang of the trailer. Basically you would have to have a very tall sitting fifth wheel trailer to be able to accomplish both of those things I mentioned and...
    view full answer...
  • 5th Wheel Trailer Hitch and Installation Kit Recommendation for 2006 Chevy Silverado 1500 Short Bed
    There are 2 short beds for the 2006 Chevy Silverado 1500; a 5-1/2 foot bed and a 6-1/2 foot bed. If your truck has the 6-1/2 foot bed than the regular slider hitch can work. But if you have a 5-1/2 foot bed the regular slider hitch will not offer enough travel to safely make 90 degree turns. For the 5-1/2 foot bed I have an excellent solution if the gross trailer weight is less than 13,000 pounds. You can use the Demco HiJacker, # DM8550040, with installation kit # DM8552009-71, for a...
    view full answer...
  • Under-Bed Rails for 2003 Chevy Silverado
    There is an under-bed rail system that will work with your 2003 Chevy Silverado 2500HD short bed, but the Reese # RP30073 you referenced only fits Ford Super Duty trucks from 1999-2010 so it would be like trying to install AAA batteries in a remote control that uses AA batteries. You may be able to get the batteries in, but there won't be any power to the remote. For under-bed rails that do work with your '03 Silverado I recommend the Under-bed Rail and Installation Kit for Demco Hijacker...
    view full answer...
  • Recommended 5th Wheel Hitch for 2004 Chevy Silverado 3500
    When choosing a fifth wheel hitch for your 2004 Chevrolet Silverado 3500, you will first want to consider the weight of the trailer that you will be pulling. You will need to make sure you choose a hitch with the required weight capacity. Since your Silverado has an 8 foot bed, you will not need a sliding hitch. Sliding fifth wheel hitches are needed on shorter beds in order to provide more cab clearance when making sharp turns. I recommend looking at the Curt Q20 5th Wheel Trailer Hitch...
    view full answer...
  • Is Demco Auto-Slide 5th Wheel Hitch Compatible with B&W Installation Kit
    The design of the B&W under-bed gooseneck install kit # BWGNRK1067-5W that accepts their Companion hitch # BWRVK3400-5W in your 2008 Chevy 2500HD short-bed does not allow use of another slider hitch, nor use of any type of adapter to allow an industry-standard type hitch to mount. You will need to completely remove the entire B&W system in order to install a Demco kit. For a Demco under-bed installation kit you will use kit # DM8551004 and either 18K slider hitch # DM8550022 or 21K hitch...
    view full answer...
  • Best 5th Wheel Towing Setup for a 2007 GMC Sierra 2500HD
    Since you have a short bed (6-1/2') on your 2007 GMC Sierra 2500HD, you will need a rolling hitch or more commonly referred to as a sliding 5th wheel hitch for your 397 Heartland Edge Toy Hauler to make tight turns. The general rule of thumb is that if you're towing a 5th wheel trailer with a truck that has a bed shorter than 8' then you will need a sliding hitch to gain clearance between the trailer and the cab of your vehicle while turning to prevent them from contacting one another,...
    view full answer...
  • Recommended Fifth Wheel Trailer Hitch For 2005 Chevrolet Silverado 1500 With 5-1/2 Ft Bed
    There are two ways you can get a fifth wheel hitch on your 2005 Silverado with the 5-1/2 ft bed. You can go with a fixed fifth wheel hitch like the M5 Series, part # RP30928. You will then need to change out the pin box on your trailer and replace it with a Sidewinder that will give you the ability to execute corners. The fifth wheel installation kit I recommend is part # RP50064-58. This is a custom kit and it cuts the installation time in half when compared to using the standard kit...
    view full answer...
  • 5th Wheel Hitch With Underbed Base Rails for 2008 Chevy Silverado 3500 With 8 Foot Long Bed
    There are a couple of options to add a 5th wheel hitch that mounts to underbed base rails on your 2008 Chevy Silverado 3500 long bed, which I'll go over for you. In regards to towing capacity, you will want to verify this yourself in your owner's manual, but according to the online manual an '08 Silverado 3500 Crew Cab 4WD long bed with single rear wheels has a maximum towing capacity of 9,300 lbs if you have a 3.73 axle ratio or 11,800 lbs if you have a 4.10 axle ratio. In regards to...
    view full answer...
  • Compatibility of the Demco Auto Slide Hitch and a Rail Adapter Kit to Fit the B&W Underbed Hitch
    I have a solution for you, but the Demco Hijacker Auto Slide 5th Wheel Hitch for Above Bed Rails, # DM8552009-71, is not compatible with using a rail adapter with the B&W Turnoverball Underbed Gooseneck Hitch. Auto slide 5th wheel hitches cannot be mounted to the adapter. Using the Demco 5th Wheel Base Rails Adapter for B&W Turnoverball Gooseneck Hitches, # DM6140, you can install the Demco Hijacker Premier Series Ultra Slide 5th Wheel Trailer Hitch w/ Slider 21K, # DM6076P-UL-21K. The...
    view full answer...
  • Will a Reese Signature Series Hitch Fit a 2009 GMC Sierra 3500 Long Bed
    There isn't an under bed installation kit that will fit the Signature Series hitch and your 2009 GMC Sierra. If you want an under bed set up you would have to replace the hitch as well. I know that isn't the best news. Your options are: B&W Companion # BWRVK3500-5W with install kit # BWGNRK1067-5W (doubles as gooseneck hitch) Demco hitch # DM8550032 with installation kit # DM8551004 Draw-Tite hitch # 9480-5W with install kit # 9465-34-5W (doubles as gooseneck hitch)
    view full answer...
  • Underbed Fifth Wheel Hitch Rails for 2006 GMC Sierra 3500 with 8 Foot Bed
    While we do have underbed fifth wheel rails for your 2006 GMC Sierra 3500, the Under-Bed Rail and Installation Kit for Reese Elite Series 5th Wheel Trailer Hitches # RP30061 does not fit any 8 foot beds; rail kits are specific to vehicle frames which are going to be different depending on their length. Though there are some underbed kits which fit both short and long beds, the Elite Series does not. There are three options for underbed rails for a fifth wheel hitch in your '06 Sierra 3500,...
    view full answer...

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