Do the driveshafts use the same u-joints....if so, is the pinion in the same location between the two (basically do they use the same driveshafts if I changed from a 70 to an 80)

 

Nope....shaft for a 70 is a bit to long to use with a 80

 

Well, I have a D70 and just switched from an auto to a 5 speed. I have a line on a rear driveshaft from a truck with a D80 with a 5 speed 4x4

Will it work?

 

I just did the swap mine was a 95 auto 3/4 ton swapped all the stuff from a 95 manual 1 ton. the one ton had the dana 80 I have the 70 and they were the same u-joint it all bolted right up it might have been longer but it bolted in.

 

they'll work swap direct. I pulled the D80 out of my '98.5 and stuck in a D70 from a '95 just before i sold it. swapped the ubolt plates and directly bolted everything back in. Surely the slip yolk will handle any slight difference in the pinion length. overall slip yolk travel in a stock setup is from full compression to full droop is very little anyways.