I have a 97 Camaro Z/28, Looking to buy a posi- trac unit call Summit Racing they ask me what size rear it had i thought all 97 Camaros had a 7.5 the guy said it was either a 7.5 or a 8.5 got the serial# Called my local Chevrolet Dealer he said that the only thing he could tell me that it had a 2.73 which i knew that all along could some of you guys help me. Thanks

 

All 4th Gen F-Bodys came from the factory with a 7.5"/7.625" 10-bolt rear axle assembly.

They had several different rear axle ratios, including 2.73:1 (RPO code GU2), 3.08:1 (GU4), 3.23:1 (GU5) and 3.42:1 (GU6)

You need to know which "carrier" the rear axle came with, and 3.08 and numerically lower use a 2-series carrier. 3.23 and numerically higher use a 3-series carrier.

 

Closing. Duplicate thread on another forum