Amplifying on Ken's response, there are some 5th wheels that cannot even use an extended pin box because of the pin weight of the trailer and the resultant torque produced by the offset of the extended pin box. As an example, if a trailer used a 12" extended pin box and had a pin weight of 2500 lbs, a static torque of 2500 lb-ft would be produced and applied to the pin box/frame area. The torque would be higher under dynamic conditions such as bumps, etc. Is a torque of 2500 lb-ft significant? Compare it to the torque produced by your tow vehicle's engine!
So, yes, I would certainly check with the 5th wheel manufacturer, NOT the dealer, to see if the frame/pin box has the capacity to handle the additional loading imposed by this RV5 king pin extender before using it.
2016 Ram Longhorn 3500 Dually 4x4 CCLB, 385/900 Cummins, Aisin AS69RC, 4.10
2014.5 DRV Mobile Suites 38RSSA #6972
Come join us on a TEXAS BOOMERS