I have a 72 Dart with a slant 6, 904, and 7 1/4 rear. I plan on swapping in a 360, 904, 8 3/4 rear into it from a 68 Dart I used to have. I may have to do this in steps. That is, swap in the rear and new leaf springs and do the rest later. Will my /6 driveshaft or the driveshaft from the 68 work...