I presently have a 69 Chevelle Hardtop and it has disk/drum brakes which will be converted to disk all the way around. I also want to put a 502 in it eventually but I want to swap a Turbo 350 to a 700 R4. I was told you have to shorten the drivesahft. My question is this if got the tranny from a 87-90 Camaro, could I use the driveshaft from that car instead? Thanx

No, It is different

Thanx that means I have to find another shaft.

If your stock driveshaft is in good shape, have it shortened.