What Base Rails Fit 2021 GMC Sierra 1500 With 5'9" Short Bed

Updated 01/05/2026 | Published 09/09/2024

Products Featured in This Question

B&W Patriot 5th Wheel Trailer Hitch - Dual Jaw - 18,000 lbs

(762)

$799.00

Question:

I have a 2021 Sierra 1500 with the 5’9” bed and I would like to install a standard fifth wheel hitch to use with the Reese Sidewinder. I am towing a Winnebago Micro Minnie 2405 which is only 7’ wide rather than 8’ so I think this should be possible with the 22” offset that the SW provides. Will the kit for the 6’6” bed work on the shorter wheelbase truck? Also, I have a Curt Q20 hitch, would that be sufficient and will the SW work with it?

asked by: Mark

Expert Reply:

Hey Mark,

Yes, the 5th wheel base rails for the 6'6" 2021 GMC Sierra 1500 will also fit the 5'9" short bed, with the correct rail kit being the following:

- Reese Quick-Install Custom Outboard Installation Kit w/ Base Rails # RP56015-53

Keep in mind rail kits won't fit your Sierra if it has the CarbonPro bed or Adaptive Ride Control. This'll allow you to mount a 5th wheel hitch with the Reese Sidewinder # RP34FR, but you can't use the Q20 because it isn't compatible.

It has a spherical head which isn't stable enough to use with the Sidewinder, so you'll need a new hitch and wedge that is compatible. You should be able to sell the Q20 pretty easily and you can replace it with the B&W Patriot 5th Wheel Trailer Hitch # BWRVK3255 and Wedge # RP74FR.

Finally, the last thing you'll need is a 5th wheel wiring harness, part # 20110.

expert reply by: Kyle S

Robin H.

1/5/2026

Hey Mark, how did things go with the Reese rail kit and the B&W Patriot hitch on your Sierra? Did the Sidewinder setup give you the turning clearance you needed with your Micro Minnie? Your update could make it easier for others towing with short-bed trucks.

Mark

1/5/2026

@RobinH Hi Robin, I ended up using the Reese rail kit and a Reese 16k hitch since the spacing for the B&W was different. The kit install was not difficult and only took an hour or so. The sidewinder also worked great and my Micro Minnie had plenty of space to turn even with the shortest box option.