I have a 1978 Trans Am with an 8.5 10 bolt posi in it with 2.56 gears the posi unit is in great shape I am wanting to put 3.42 gears in it but everything I see says the housing has to be 2.73 or above to make that work but I have been told they make a thicker ring gear to make up the difference does anyone know if that's true ? I have seen spacers to make it work but I'm not very crazy about using a spacer.
I agree. I built an 8.5 that had it's original 2 series posi carrier,so I also thought about using the thicker ring gear. I talked to Jim at JD race and Randys ring and pinion and they confirmed that the thick ring gears are only made for the Chevy type 12 bolts.
71' GTO Original 400 M20 3.23 posi email@example.com MPH on street tires