Recommended Gooseneck Pin Box for a Lippert 1621 that Works w/a Flatbed Truck w/a Recessed Ball

Updated 06/09/2026 | Published 06/08/2026

Products Featured in This Question

Gen-Y Hitch Shock Absorbing 5th Wheel to Gooseneck Pin Box - Lippert 1621/1621HD - 30K GTW - 4.5K TW

(328)

$1799.95

Replacement Base for B&W Companion 5th Wheel Trailer Hitch - 20,000 lbs

(97)

$616.36

B&W Companion OEM 5th Wheel Hitch for Ford Super Duty Prep Package - Dual Jaw - 25,000 lbs

(5726)

$1499.00

Safety Chain with 2 Hooks for Gen-Y 5th Wheel to Gooseneck Pin Box - 84" Long - 26,000 lbs

(278)

$100.95

Question:

Good afternoon, I have a different set up I was hoping to get some of your expertise with on ordering a goose neck Adapter or Replacement pin box. I have Ram 5500 86” Cab to axle CM Flatbed with a built-in gooseneck ball. I have added top boxes to the bed as I typically use this truck for my truck bed camper. The Truck is Slightly lifted and on larger tires, The Top of Goose neck ball is at 44” from the ground and 64” from end of bed and hitch mount to center of the ball. I would like to be able to use the truck to tow my Grand Design 399TH Toy Hauler, it has a Lippert 1621 21k Fifth Wheel Mount. Ideally I would be able to use a goose neck adapter with a long enough Coupler Pipe to keep the Top Boxes on and still have the toy hauler ride level. I think that if I change the entire pin box out I would leave the toy hauler set up as a Gooseneck and again hopefully be able to still have the clearance over the top boxes. Would you please check with your team to see if anyone has assisted with a similar set up or has any options that would work. Possible Other Option: I recently sold my F450 that was set up with a BW 25K Companion Puck Mounted Fifth Wheel Hitch, I still have the hitch if using this is an option at all. I do not see a conversion mounting plate other than possibility of having a puck system welded in the CM bed Which I do not think is a cost-effective route to go.

asked by: Stephen F

Expert Reply:

Welcome back Stephen. The Gen-Y Hitch Shock Absorbing 5th Wheel to Gooseneck Pin Box item # GY38FR is going to be the best option for clearance and fits a 1621 bolt pattern. 64" is a big distance to cover though. I attached a complete schematic below that will show you every measurement you'll need to determine if you have enough clearance.

Please note that the Gen-Y item # GY38FR requires a recess well that has at least 5" of clearance around the gooseneck ball.

You will also need the Safety Chain with 2 Hooks for Gen-Y 5th Wheel to Gooseneck Pin Box item # GY49GR. Safety chains are required for gooseneck connections and they are not included with the pin boxes. These will attach to that cross looking cutout by the Gen-Y logo.

As far as reusing your B&W Companion item # BWRVK3305 goes, the only thing I can offer is a replacement base that fits another OEM puck system or the B&W's Turnoverball gooseneck hitch item # BWRVB3500. I don't see a viable way to use it with your current setup at all.

How tall and wide are your toolboxes and what kingpin pin box is currently on your Toy Hauler?

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