Can Convert a Ball Adapter be Used with MORryde Pin Box and Knapheide Flat Bed PGTB-708-R

Updated 05/18/2026 | Published 05/15/2026

Question:

I have a 2011 Ram 3500 Crew Cab. I removed the box and installed a Knapheide flat bed PGTB-708-R. This is for short bed trucks, the flatbed is 7foot in length with tapered back edges clearance while turning. The flat bed has BandW turn over system mounted into the flat bed and is rated for 30K, it also flush with the surface of the flat bed and is not in a recessed well. All measurement were taken level ground. Flat bed deck height is 42, Bottom of the fifth wheel is 65 1/4. Off of the deck of the flat bed to the king pin is 6 3/4inch from the deck of the flat bed to the friction disk is right 9 3/4 to 10. I have a MORryde RPB72-1621HD rated at 18K, this is attached to a Lippert 726697. I will be cutting down the headache rack on the flat bed so its apx 3 - 4inch below the bottom of the rear window. Also I have no side rails on the flat bed. Im looking at this because of the offset and its also cushioned and it would requirement to purchase a new pin box. 1st question can this be used with the MORryde? if yes do I need to buy the MORryde heavy duty king pin plate? 2nd question, If NO what are my options?

asked by: Tom J

King Pin Dimension
(click to enlarge)

Expert Reply:

Hey Tom, thanks for all of the dimensions of your bed and fifth wheel pin box. Usually with flat beds you have to have the rail system recessed because the bed height is taller than stock truck bed heights but your bed height seems to be same height as the stock bed so you are good in that regard.

The Convert a Ball Offset Gooseneck hitch adapter part # CAB-C5GX1216 can be used with the MORryde pin box you have as well. I've confirmed this with MORryde in the past and you would not need a heavy duty king pin plate either. Does your fifth wheel trailer have a tapered nose?

expert reply by: Jameson C