I'm not understanding your question?????
Our you looking to get the Trailair and use it on next 5th wheel
Reusing the Lippert 1621 on your next 5th wheel
Lippert 1621 is a common 'long' pin box
Pin Box is the removable part that bolts to trailer pin box frame/structure/mounting plates.
Next trailer might have different mounting and then again it might be same.
Pin Box Measurements/Info