904's use the same drive shaft regardless of motor in front. 727's and 904's will mount right up to the cross member.
Different length drive shafts on:
904 vs 727. 727 is longer requiring a shorter drive shaft. Also, 904 and 727's have different yokes
as mentioned above, the rear end has an effect on the length.
In short, you can pull a slant/904 and drop in a V8/904 and the drive shaft will be correct
