C3 Corvette Differential and Axle Codes 1977 to 1982

Decoding your rear axle code

This page covers 1977 to 1982 Corvettes. On these cars, Chevrolet stamped a short code into the differential housing itself, low on the case near where the leaf spring mount bolts up, identifying the rear axle ratio and some build information such as the assembly plant and build date. It is a tight, often grimy spot to find, and the stamp can be hard to read without cleaning the area first.

The axle code tells you what final drive ratio the car left the factory with, which affects everything from acceleration to highway RPM and matters for anyone verifying originality or comparing a car's performance to its factory specification. The table below lists the codes used from 1977 through 1982 and the ratio each one represents.