Need some more info. What happened to your driveshaft? Is it a two piece? I was under the impression SWB trucks all came with a one-piece? Did you use something other than a GM rearend? If you need your driveshaft shortened, I had mine done for $15 at a local shop. If you need it lengthened, I see your dilemma. Go to a 'yard and start measurin
Edit, when I put a 700R4 in my truck I had to find an automatic splined shaft so I thought, why not try to find one that will already fit, not sure on your tranny lenght, but trips to 3 yards didn't come up with a match. I ended up adding the automatic yoke and takin it to a shop.