King Pin Box to Fit Leland AF 7921 Bolt Pattern

Updated 07/22/2025 | Published 03/26/2021

Products Featured in This Question

Reese Goose Box 5th-Wheel-to-Gooseneck Air Ride Coupler Adapter - Lippert 1716 - 20,000 lbs

(324)

$1658.57

Trailair Air Ride 5th Wheel King Pin - Leland 7920 - 21,000 lbs

(83)

$1625.07

Question:

Will one of the 16K Reese Goose Box models fit a Leland AF 7921 pin box and would it provide enough cab clearance for a 2018 Ram 3500 Mega Cab Short box? Trailer is a 2004 KZ Durango 29BH.

asked by: Mark D

Expert Reply:

None of the Reese Goose Box models fit the Leland AF-7921 pin box wings/flanges, but there is another solution. There are only two king pins that fit the Leland bolt pattern, those being the Trailair # UF35-946208 5th wheel kingpin and the Reese # ST400-5AS16K 5th wheel king pin with sidewinder turret.

The Trailair is a traditional king pin with an air ride shock which offers a smoother ride, but only traditional limited turning clearance. The Reese 5th wheel moves the rotational point 22" furhter back allowing near 90 degree turns for most truck/trailer combinations. Both of these king pins will require a tratitional 5th wheel hitch in your truck rather than using a gooseneck ball.

The last oportunity would be to have a skilled shop cut off your current Leland flanges and weld on flanges that will accomodate the Reese goose boxes.

expert reply by: Les D

Chris L.

7/19/2025

What wedge would be needed to couple the Reese # ST400-5AS16K to a B&W Companion 20K 5th wheel hitch?

Robin H.

7/20/2025

@ChrisL you need the 5th Airborne Custom Wedge for B&W Fifth Wheels # SWW-06.

Chrisl

7/22/2025

@RobinH, I was told that the Reese Sidewinder that fit the Leland AF-7921 pin box wing set has been discontinued. I have a 2007 Jayco Eagle with this pin box. My truck is a Ford F350 with the short box. I'm looking for the best option to go with. A slider hitch is not really an option because of the limitation of needing to hook and unhook straight on. I also need the pivot location to be around 22 inches back from the axle to get the maximum turn angle. What options do I have that with meet my needs?

Chrisl

7/22/2025

I was toldby my local dealer that the Reese Sidewinder that fit the Leland AF-7921 pin box wings/flanges has been discontinued. I have a 2007 Jayco Eagle with this pin box. My truck is a Ford F350 with the short box. I'm looking for the best option to go with. A slider hitch is not really an option because of the limitation of needing to hook and unhook straight on. I also need the pivot location to be around 22 inches back from the axle to get the maximum turn angle. What options do I have that with meet my needs?