"I know the game ford and ram are playing with their gvwr rating on the 450/4500 trucks. I also know the rear end in the f450 is a step up from mine, I assume the ram must be also."
The RAM 4500 is only a Cab and Chassis the F450 is available the same but also with a pickup bed. All 350/3500's in a DRW are 14K GVWR Class 3, Ford chooses to keep their 450 in the same weight rating.
The reality is the GVWR on all Dually trucks should be higher but the licensing and insurance keep them at 14K.
If over 14K be sure to get 16K tonnage.