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Review of Demco Fifth Wheel Installation Kit - DM6333

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Demco Fifth Wheel Installation Kit - DM6333 Review

Today, we're going to take a look at the Demco fifth wheel rail adapter for the Chevrolet and GMC OEM fifth wheel towing prep package, and it has a 21,000 pound weight capacity. Now, this is a custom fit part. It is designed to fit the 2020 Chevrolet Silverado and GMC Sierra 2,500 and 3,500 trucks with that OEM fifth wheel towing prep package. On a custom fit part like this, I always like to recommend for you to go to our website, use the fit guide, put in your year and model vehicle. It'll show you if this'll work for your application. Basically, this will convert your factory-installed under bed fifth wheel mounting kit from Chevrolet or GMC to the standard above bed fifth wheel base rails.

And, it'll allow you to use your fifth wheel trailer hitch that attaches to the standard above bed base rails. These do mount to the OEM pucks or sockets that are in your truck bed.The unit will drop into the pucks and then you lock it into place. There's no drilling or welding required. What I want to do here is.. It's hard to see, so I'm going to try to raise this to show you those.

You can see them right here. This is what'll drop into those pucks that are on the factory system, and what you'll do is just pull the pin out and then rotate these handles. And, you can see as I rotate the handle, it'll rotate the tab right here, and when you open both of them on all four corners up, then you can drop it right in place, rotate the handles back and then drop the pin right through there. That'll lock it into that factory system. You can see this has a nice rust-resistant black powder coat finish on it.

It's a steel construction. It is made in the U.S.A. Application, again is for Chevrolet or GMC trucks with the OEM under bed base rails. Maximum capacity is 21,000 pounds. Maximum pin weight capacity is 6,250 pounds.And, what I'm going to do now is show you the handles again.

I just want to show you where those tabs were. Here's the handles. You can see the pins right here. If you pull this pin out, you just rotate these handles out like that and do the same over here, rotate the handles out. Now, those tabs are all in the open position, drop it into the pucks that are in the bed. Rotate both of these handles back. Put that pin back in it. The pin has a nice indentation or an indent on it that'll hold it in place. Same way, rotate these back, and as you're rotating those handles back, it's rotating those tabs to lock it into that factory system, but that should do it for the review on the Demco fifth wheel rail adapter for the Chevrolet and GMC OEM fifth wheel towing prep package. And, this has a 21,000 pound weight capacity..

Pat A.


An Instruction sheet came with the adapter but it only described a fit problem that had to do with removing the bottom nut from the puck assembly. My problem was solved by loosening the 4 bolts on top of the puck assembly. Where in your documentation does it describe this adjustment?

Etrailer Expert

Jon G.


Step 2.

John C.


@PatA I had the same issue. I loosened all 16 bolts (4 on each corner) which allowed it to drop in. I expected a plug n play setup as well but this did work. I do have some play in the adapter/ truck which causes some hitch noise. I am looking in ot adding some shims to pick up the slack.

Tony B.


It does not just drop in.i worked it for an hour. And still no go. The install says to disassemble the handles and pre fit them to make sure they go. Then reassemble and try again

Etrailer Expert

Jon G.


The instructions for the Demco 5th Wheel Rail Adapter # DM6333 essentially says that it will drop right in but if it doesn't then they give you a way to make an adjustment so it can fit. What is the year/make/model of your pickup and what is the length of your truck bed? It could be that you have the wrong adapter rail kit.

Dennis K.


I have a airsafe hitch. What are the measurements between slots for hitch, frount to back and side to side.

Etrailer Expert

Chris R.


Front to back on the Demco Rail Adapter # DM6333 the mounting slots are spaced apart by 22", which is industry standard. I've linked an answer page below that shows a nice diagram of the adapter's dimensions - included the side-to-side spacing.

Dennis K.


@ChrisR thanks

Etrailer Expert

Chris R.


@DennisK No problem at all.

Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video by:
Chris R
Employee Adam E
Test Fit:
Adam E

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