jimnance, I understand it to be that all 3500 Dodge's come w/ the Dana 80 and the 2500 HD Dodge's with a CUMMINS/ Standard trans or a V10 and a standard trans come w/ the Dana 80.
There are some hub and brake differences between the 3500 and the 2500 Dana 80's.
Most Dana 80's that come in larger trucks ( F-450's and older GM 3500H. D. 1-1/4 TON trucks usually have larger hubs and bigger axle shafts. Our Dodge's come with hub's and axle's much like the H. D. Dana 70's. HTH, Thomas