There are some differences between 8.5's. I've heard that if your 8.5 yoke uses u bolts (like the 8.2) then your driveshaft will fit.
My 8.5 used bolts and straps, and my driveshaft was a lil too long.

 

DXriveshaft length shold be the same...you will likely need to change the U-Joint though (1310 to R3)...please see this thread for U-joint info, and spicer part number:

http://www.camaros.net/forums/showthread.php?t=164199

 

thx guys.havent got the rear yet to see the u joint.mabe tomorrow

 

Apparently, if the Nova rear has a 1310 yoke, you can re-use your driveshaft, but if it has the newer 3R yoke, you'll need to either shorten the driveshaft or replace the yoke. Spotty info on when GM changed from the 1310 to the 3R, but it appears to be "somewhere" around 1976 (the '74 Nova rear I just picked up has a 1310)

Credit this info to Eric Kammerer:
http://www.camaros.net/forums/showthread.php?t=93677

Also, assuming you're going from a mono-leaf 8.2 to a multi-leaf 8.5", the lower spring mounting plates and shocks are different. The mono-leaf parts can be made to work on the multi-leaf rear, but it moves the bottom shock eye down which can cause the shock to interfere with some wheels. You can also end up with "too short" of a shock then, which is not so good. Best bet is to use replacement multi-leaf shock plates (DSE makes some beefy ones) and either get the bolt-in stud that will let you re-use your old shocks or replace the shocks as well.

-T

 

thx good info