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Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package - 21K

Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package - 21K

Item # DM6333
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Accessories and Parts DM6333 - Rail Adapter - Demco
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Use your standard, above-bed fifth-wheel trailer hitch with your Chevy or GMC factory, underbed 5th-wheel towing prep package. Adapter mounts in factory sockets and supplies mounting rails in your truck bed for attaching your hitch. Call 800-298-1624 to order Demco accessories and parts part number DM6333 or order online at etrailer.com. Free expert support on all Demco products. Guaranteed Lowest Price and Fastest Shipping for Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package - 21K. Accessories and Parts reviews from real customers.
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  • Q & A (183)
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2022 GMC Sierra 2500 - Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package - 21K

  • Fifth Wheel Installation Kit
  • Rail Adapter
  • Demco

Use your standard, above-bed fifth-wheel trailer hitch with your Chevy or GMC factory, underbed 5th-wheel towing prep package. Adapter mounts in factory sockets and supplies mounting rails in your truck bed for attaching your hitch.


  • Converts your factory-installed, underbed 5th-wheel mounting kit from Chevy or GMC to standard, above-bed 5th-wheel base rails
    • Lets you use your 5th-wheel trailer hitch that attaches to standard, above-bed rails
  • Mounts to OEM pucks (or sockets) in your truck bed
    • Unit drops into pucks and locks in place
    • No drilling or welding required
  • Rust-resistant black powder coated steel construction
  • Made in the USA


  • Application: Chevy or GMC trucks with OEM, underbed base rails and 6-1/2' or 8' beds
  • Maximum capacity: 21,000 lbs
  • 5-Year warranty

Note: This adapter will not work with a B and W Patriot sliding hitch.

This adapter is perfect if you want to use your standard fifth-wheel trailer hitch with your Chevy or GMC truck's factory-installed, underbed fifth-wheel mounting kit. Just mount the adapter in your underbed rails using the integrated pucks and lock it place. Now you have the standard, above-bed base rails needed to install your fifth-wheel hitch.

6333 Demco Chevy or GMC Truck OEM Adapter for Attaching Standard Fifth-Wheel Trailer Hitches

Installation Details DM6333 Installation instructions

California residents: click here

Customer Reviews

Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package - 21K - DM6333

Average Customer Rating:  4.8 out of 5 stars   (181 Customer Reviews)

Use your standard, above-bed fifth-wheel trailer hitch with your Chevy or GMC factory, underbed 5th-wheel towing prep package. Adapter mounts in factory sockets and supplies mounting rails in your truck bed for attaching your hitch.

- DM6333

This adapter allowed me to use the Curt A16 hitch I already owned. This DEMCO 6333 adapter is an absolute monster. Incredibly well built with precise machining. The hitch fits very well. Since each truck is built within a certain tolerance and slightly different I had to make a minor adjustment to the lock down positions to get the perfect fit. By loosening all 4 bolts on each of the lock down handles I was able to get the adapter to drop right in place. Comparing this adapter to others is no comparison. This DEMCO 6333 is much sturdier. I added a picture of the Curt A16 mounted on the DEMCO 6333 under the LUND Tri-fold cover. Overall, this is a great combination. I wanted to be sure to say "THANKS" to Montrell (etrailer Rep) who ensured the DEMCO was a proper fir for my truck as well as processing the order quickly. Job Well Done!!

- DM6333

I got a new 2021 GMC with the puck system and I wanted to be able to use my existing Pullrite Superglide 2700 hitch. I looked at the Pullrite adapter...that's a multi-piece rail system and was thinking more likely to rattle. Found this Demco adapter which is one piece and a better price. Just put the adapter (and the hitch) in the truck this morning. Following the instructions, loosened the bolts and it dropped right in. The only thing that would've made this better is if the temp was above freezing.

- DM6333

Very easy to installed and remove.The only thing I don't like is that it doesn't lock in tight. And when the 5th wheel is hooked up to the camper you can hear and feel the rail adapter moving when you taking off and slowing down.

Thank you for your review! A few things to keep in mind when using this adaptor. Since it can be used with different manufacturers, there may be little bit of play in how things fit from brand to brand, and in the puck openings, dirt and debris can get caught there, too. If it were a perfect fit, the debris would eventually lock the adaptor in place permanently, the having a little but of room helps prevent this from happening. I hope this helps!
-- Etrailer Expert Brooke M - 08/09/2021

- DM6333

Would make life a whole lot easier if you could actually reach the lock pins for the levers with out removing the whole fifth wheel hitch that is mounted to it so that you could remove the whole system at one time.

- DM6333

Easy installation.

- DM6333

Excellent service, was able to ship my item to me in 3 days!!! Will always refer friends and family to etrailer! The Demco 6333 fit my 2020 Denali dually perfect so I could keep my 5th wheel hitch...

- DM6333

Outstanding product. But even more outstanding was Customer Service and expert technical advice. All questions to the technical experts were processed fast and right on with correct answers. Customer service was unbelievable. I called them with a concern on shipment that was being held up. They got right in it and before the evening was gone my shipment was. Processed and at my house in three days. I was in a bind to move my fifth wheel and without a working hitch in my new truck. They came through with the product and shipment so I could move my camper and not have any issues. As others have said, etrailer is above others on customer service and reliability of product and great technical help. My choice of business when I need something or have to have the correct technical data. Thanks for the extra effort.

- DM6333

I have had Reese adapters for Ford and Ram and the Demco is by far the best built for ease of engagement and adjustment there is. Great job DEMCO!!

- DM6333

Easiest puck system plate I have used in the last 3 GM trucks I have owned.

- DM6333
2020 Chevrolet Silverado 3500

I love the adapter. Received it really fast, and it dropped in and fit really well. I have a 2020 Chevrolet Silverado 3500hd, with fifth wheel prep package. I also have a Curt E16, with A16 slider to use on it.

- DM6333
Dodge Ram Pickup

This is an excellent product to use for the Demco auto slider 5th wheel. Follow the directions and it will drop right into the pucks. It's heavy so it will take another pair of hands unless you're Arnold. I'm alone, so I have a 2 ton engine hoist that works real well. My auto slider drops right into adapter rails. An excellent piece of equipment from etrailer. Best place to buy rv equipment. When needed, they're an excellent choice for advice. I might add that this adapter is only for the 2020 Silverado and GMC Sierra. They have different ones for Ford and Ram. I would definitely buy from etrailer again.

- DM6333

Thank you and the product is everything I was looking for. All aspects of the service was great . Again Thank you

I installed it and walked away with no issues- highly recommended
Scott - 06/06/2021

- DM6333

I recently purchased the Demco autoslide 5th wheel hitch with the 21K rail adaptor wih tow prep package. I installed everything in less than two hours, I found it to be pretty simple to put together. The puck system fits like a glove to my truck. I planned on keeping the two parts together all the time, but it is a little difficult to unlock the puck system with the hitch still attached. My hitch width covers the safty pins that lock into my puck system. Not a big deal, I may find it's easier to take the hitch off then the adaptor. My wife and I don't have a trailer yet, but when she finds the one she wants we will be ready for the road!

- DM6333
Chevrolet Silverado

First time using etrailer. The whole process from ordering to delivery was great, placed order on Tuesday and received it on Thursday. I was kept informed through the entire process. I ordered the Demco dm6333 adapter to be used with a Pullrite 2700 SuperGlide that i already owned. Used the dm6333 adapter in a standard bed 2020 Silverado 2500 that had factory pucks. Had to loosen the bolts on the locking handle plates to get the adapter to drop in the pucks but that was expected from posts I saw on line, no problem. Mounted 2700 SuperGlide to adapter just fine. Trailer is 7 inches above bedrails and good clearance when turning. Trailer is about 2 inches from level but I don't think that is a problem. Demco's dm 6333 seems to be what i needed without having to purchase a new hitch.

- DM6333

I have a 2020 Chevrolet 2500HD with the OEM puck system and standard bed. I am moving from a travel trailer to a fifth wheel trailer. The trailer trade developed pretty quickly so I was in need of a quick solution (time wise) for my truck. Honestly, I intended to purchase the Curt bed rails but they were out of stock. The Curt was a little lighter in weight, making it a little easier to remove. The delivery of the Demco rails was fast and showed up damage free. It is heavy and you can see why it's rated at 21,000 pounds. As others have said, I did need to loosen all the handle mounts to get it to fit into the bed pucks. Wasn't a big deal. The only other issue was the height of the rails. The top of the rails is 2 3/4 inches above the truck bed. Factor that in when you look at the height of the fifth wheel on this truck. All in all I'm pleased with the product, just a lot heavier than I would have liked. As always, etrailer was great to work with and very responsive on the shipping.

- DM6333

Excellent product, I bought a 2020 GMC diesel the rail adapter fit perfect. As you can see in the picture, a husky fifth wheel hitch fit this adapter. The instructions that come with the adapter made it easy to install.

- DM6333
2020 Chevrolet Silverado 2500

Received product and fits fine. I would suggest one thing for etrailer. If you do not have the product in stock, tell the customer when ordering, not two or three days later. not a problem so much, but would have like to know when ordered. Fast shipping when you received the product & no problems installing.

Very good.
Wayne - 12/06/2020

- DM6333

Just received the adapter and 15 minutes to install. However, you likely will have to loosen the 9/16 bolts on one side to get it to drop into the puck holes then torque back down. Mine was just a 1/32 off and would not drop until I loosened the bolts which allowed the locking tabs to drop into the puck.

- DM6333

Adapter arrived earlier than promised. Was able to install it with help from my son without any problems and my existing hitch slid right onto it. Thanks Gwen for the great advice and service!

- DM6333

Researched for best price and found etrailer had the best price and I got the Adapter hitch the day it was promised.

- DM6333

The adapter fit my 2020 GMC 3500 like a glove just like Korren said it would.I ordered it on a Thursday and got it the following Tuesday.

- DM6333

It fits the new 2020 Gmc / Chevrolet And has two different sized hitch connections for US standard hitches you got to loosen up where the handles are with a wrench set it down make sure they lineup and then tighten it down and snap it in

- DM6333
2020 GMC Sierra 2500

I had to make some adjustments. Per the instructions and it works like a charm. Great product. Thanks the video in the like help me pick this.

C - 07/02/2021

- DM6333

Even though the base plate is made for my truck it still moves a bit which makes it seem as though it is not tight enough for the setup.

- DM6333
2020 Chevrolet Silverado 3500

Product is very well built. Installation would have went much quicker had there been directions explaining to loosen the 4 9/16 bolts at each handle to allow play for the adapter to fall into pick system. Then retighten bolts. What should have taken 10 minutes took over an hour and reading others reveiws.

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Jameson C
Expert Research:
Jameson C
Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video by:
Chris R
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Written by:
Kristina F
Employee Adam E
Test Fit:
Adam E

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