is a good reference source for Nova drive trains. The "rules" were sometimes broken, however. Occasionally, due to parts availability problems, they would use a stronger rear or trans than spec called for, in order to keep the assembly line operating, but it was only once in a while.
has pics of how to tell an 8.5" rear from a 7.5".
The Camaro/Firebird 8.5" rear will NOT bolt into a Nova. It's too wide, and the spring perches are too far apart.