I'm not "sure" if you have to shorten the driveshaft (others here know). There is some play in the transmission yoke end of the driveshaft, so if the dimensions of dana vs. 8-3/4 are really close, you might be OK. There are basically two u-joints for these years (big & little....3" and 3-1/2" roughly if I remember correctly). If the u-joint size is the same, you're golden. If not, they sell some conversion u-joints (one side 3", other side 3-1/2"), so you're still golden. FYI-I believe those conversion u-joints are stock in 1957 Pontiacs or Oldsmobile with the end caps swapped. The only thing I can think of that might hold you up is the speedometer gear in the transmission if the rear end gears are different.