Rear driveshaft question

[Paul72]

I'm down to the final part needed to get the Sierra Grande on the road, and I'm finding great difficulty locating it......

I put in a 700R4/208 and need a rear ds. I brought the '84 blazer shaft (trans/transfer case donor) and the original 72 shaft to the local driveline place, and they said they couldn't get a 4-1/2" yoke to weld on for the slip yoke. The local custom weld shop doesn't want to tackle the job either.

I'm looking for an 81-87 driveshaft, but have not been able to find one. What changed in 1988? I'm guessing the spline count? Can I use a 1988+ ds and swap the yoke? I know it would need to be shortened, but I'm interested in the yoke end working first.

I've got a yoke and a driveshaft, but not the piece I need. Any info on the driveshaft changes over the years would be most welcome.

I've tried all the local boneyards and nobody has a 3/4 ton ds that would work (81-87). I have also searched the web for a good on-line parts locator, but have yet to find a decent one. Again, any help would be appreciated!

Thank you,

Paul