Ford's 2014 diesel F350, auto transmission 4x4 6.7L DRW 3.73 axle ratio......
and
RAM's comparable 2014 3500 AISIN (auto transmission) DRW 3.73 is rated to tow 23,500,
Actually your not comparing apples to apples here. The Aisin transmission uses a 1:1 direct gear ratio and requires a 4.10 axle ratio to achieve max tow ratings of 29000 lbs.
Fords Torqshift 6R140 has gear splits on both sides of 1:1 so with the 3.73 rear axle ratio operates like a 4.xxx-4.30 axle ratio (depending on transmission gear selection) to achieve max towing rating.
The Ram Body Builders Guide
clicky link shows all the tow rating for each configured package truck.
Look in the notes and it mentions over 17000 lb requires a GN or 5th wheel hitch for a 3500 Ram.
If your buying a fith wheel trailer I wouldn't worry about conventional trailer (TT) weights.
