New Richmond EXcel ring and pinion set. This is a 3.42:1 gear ratio (41-12), for a 3-series carrier. Fits the following:
70-81 Camaro w/ 10-bolt 8.5" differential, 3-series carrier
70-81 Firebird/Trans Am w/ 10-bolt 8.5" differential, 3-series carrier
NOTE : 70-81's came with 7 different gear ratios. This gear set will only bolt to a 3-series carrier. If you have a 2-series carrier, you will need to purchase and install a ring gear spacer for the gears to mesh properly. Special tools such as a shop press & bearing pullers are required to install a gear set. Gears must be shimmed properly to avoid both noise and failure. These should be installed by a qualified mechanic.
2-series carriers : 2.41, 2.56, 2.73, 3.08 factory installed ratios
3-series carriers : 3.23, 3.42, 3.73 factory installed ratios