...There's no upper overload on the 2500.
Some have a lower overload, some don't.
I think there was a camper/payload package that gets the lower overload.
The 3500 has an upper and lower.
So it's a (sorta) simple addition, or just swap the whole pack.
There was no "camper package" pe se offered on the 3G Dodge trucks. There was an RV option which was 7pin, higher amp alt, etc, but nothing for hauling a camper. Heck 3G's didn't even come with a stinking sway bar!
As far as swapping the "whole pack"... I do not believe that 2500 series Dodges have the upper perch mounted to the chassis... that
"thingy" for the upper overloads to contact when weight is applied. With the exception of this item I will agree that a direct swap would be relatively easy, but not necessarily cost efficient.