Chevy,
It's pretty unlikely that your original driveshaft will be the right length. The only way to tell would be to know the length of the new transmission. Also, you would need to know if you're going to use a mechanical or a hydraulic clutch -- 350s built for automatic transmissions don't have the boss on them for the Z bar.
These forums are mostly dedicated to trucks pre-73. You'll probably find more people with experience on '77s in
http://www.67-72chevytrucks.com Brian
