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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

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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. 1-800-940-8924 to order Demco accessories and parts part number DM6333 or order online at Free expert support on all Demco products. Great prices 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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Demco Accessories and Parts

  • 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

Item # DM6333

Installation Details DM6333 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

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   (237 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.


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!!

Its been a year and about 5,000 miles. Overall The Demco works well. I dont like noisy, clunking fifth wheel hitches. With some shim adjustments I am able to keep the Demco plate snug in the built-in GM adapter.
John - 04/25/2022


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!

Still working great!
Christopher - 08/01/2022


I was disappointed with the quality of the hardware on the adjustment points for the lock mechanisms. One of the bolts was stripped out on one of the rotating lock mechanism adjustment points.

That is definitely not the standard for Demco products. I sent your information to customer service to assist you with getting those bolts replaced.
-- comment by: Heather A - 08/22/2022


Had purchased a Demco slide hitch for our Nissan TitanXD. Sold that truck and ordered this hitch plate for our 2023 GMC 2500HD. Perfect fit. Great customer service and support.

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.

After a year, still pleased with the Demco dm6333 hitch adapter, works for me.
Dennis - 02/03/2022


Would not buy again!!! The welds that hold the pins in place broke free. Looks like no weld penetration. Each pin has four welds holding in place. One pin came completely loose, all four welds broke loose. Two others pin only held in place by one weld, I could have slid a dollar bill under the other three welds. So three out of the four pins that hold the base plate to the truck had failed. I’m so glad I made it home after my last trip and I’m so glad I caught the issue before this trip. Luckily I have a welder and was able to repair myself or my trip would have been ruined. I don’t recommend this product, major safety hazard!!!!


After having this hitch for one year, I’m pretty disappointed. This hitch has the most play of any hitch I’ve ever had. The curt hitch I have has no play. Also the the handle for the slide is not very user friendly. If you pull it too hard it will simply pull out of one side. It will get the job done if you don’t have any other choice. The only reason I purchased this brand was because it was the only brand I could get during Covid.

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.


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.


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.


The demco adapter and fifth wheel have worked flawlessly on my GMC. I have never had to worry about my clearance with the auto slide fifth wheel and with a standard bed on my truck that is great. The height clearance is perfect on the bed with the various adjustments allowed on the fifth wheel. The installation was easy and the fifth wheel can be easily removed with an engine hoist. It takes about 10 minutes. I really like this product and would highly recommend it...


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.


This product was an exact fit for new GMC. Worked well with our fifth wheel hitch we already had. So glad for this adapter plate saved us a lot of money.


Everything dealing with purchase was better than expected. Super fast delivery.

2022 Chevrolet Silverado 2500

I was able to order however I needed help on some technical questions bet could not get anybody on the phone, parts came in however I needed another part to complete my order, I had to call the manufacturer of Demco and they were very helpful, now it’s going to be two more weeks before I get another part so I can haul my RV. The products are Demco 5 th wheel slider, it seems to be made well however I wont know until I receive another part.

Sorry for the confusion. Yes, item #DM8550034 goes with the installation kit.
-- Etrailer Expert Sierra K - 10/19/2021


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...

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.

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.


Fits my 2021 Chevy perfectly. Very heavy duty, but it can still be handled by hand. Since the locking pins are adjustable, it is easy to get it to drop into the pins. Fits the Demco 5th wheel as it should, just drops right into the slots without having to adjust anything. Locking pins go right in also without having to adjust anything


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.

2020 Chevrolet Silverado 3500

Just had to make a small adjustment to fit the puck system but in the end, fit perfectly and seems fairly tight. My Reese slider hitch fit perfectly.


2 of the 3/8”-16 bolts for the brackets on the locking levers were missing. I attempted to remove 1 bolt from a bracket that had all 4 and place it in the bolt hole only to find out that the threads were stripped out. Long story short I went and bought new bolts and a tap and die set and made the needed repair.

I am sorry to hear about the missing bolts. Customer Service will be reaching out to you.
-- Etrailer Expert Sierra K - 10/14/2021


It fits the new 2020 Gmc / Chevrolet
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

Ram 2500

I owned a fifth wheel hitch that was a bolt in style for my Ford truck. I purchased a new GMC 2500 that I had equipped with a factory installed puck system. This Demco adapter made it easy to keep and reuse my hitch. Worked great.


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

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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:
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Employee Kristina F
Written by:
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Employee Adam E
Test Fit:
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