Drive shaft for a 70 longbed with a 700R4

[Treetop839]

I need help trying to figure out if there is a newer model drive shaft that will fit in my truck. I have a 1970 longbed that was a factory 307/350 combo. I now have a 350 and am putting a 700R4 in. My 350 turbo is a short tail shaft model so the 700R4 is about 3 inches longer. A friend of mine says that the 88to 98 body style truck one piece drive shaft will bolt in with no modifications to the drive shaft. He has done this on three 72 models, but he can not remember what the shaft came out of. Does anyone know what year and model chevy the shaft comes out of to fit my application? I have tried several shafts from a local Junk yard but with no luck. Thanks in advance.