1965 Dodge Dart Charger

The brakes on a 8 3/4" axle was that 10" like the 7 1/4" axle which means the same brake area?

If a 8 3/4" rear end was ordered, was there a difference in the length of the prop.shaft?

Yes with a 10 inch brake the shoes and drums were the same with 8 3/4 and 7 1/4

Yes the 8 3/4 had a shorter shaft