8 3/4 identification

Being an older style 741 case does that change anything? Does that cause issues with axle shafts or fitting in the housings? What exactly is the difference between the old and new style cases.

The 1957 to 1964 8 3/4 rear ends are ok to use but the axles and pumpkin are not interchangable with the1965 and up 8 3/4s.