Thanks Rick. It looks like all the CR- codes have an exact match with a CO- code. Also noticed that there are four codes for a 2.56 open diff, COA, COB, COM, as well as CRF.
The Nova rears were one inch narrower, and the spring perches were not the same distance apart. The highest ratio listed by Colvin for a 1970 Nova is 3.55 (CBT). What's in all those Deuces?
-Sam