i hane 1980 berlinetta with a 10 bolt rear diff in it. i i know GM made different 10 bolt rears so i need to know how to tell which one i have and how to tell if it's a posi unit or not

thanks
brad

 

'71 to '81 Camaro's came with the 8.5" 10 bolt rear end with 28 spline axles. Whether it has a posi unit or not, honestly, you'll probably have to pull the diff. cover to verify that. You can try jacking up the rear of the car. Place it securely on jack stands and turn the drive shaft. Usually if it has a posi unit, the rear wheels will both turn in the same direction. Usually if it has an open diff. the wheels will turn in the opposite direction. Pulling the cover it the best way to know for sure though.

 

Or just jack up one rear wheel and put the tranny in neutral. Then spin that wheel and if it turns it isn't posi. If it wont turn it is posi.

 

thanks very much, i shoulda thought about spinning the wheel tos see what direction they turned.
now to figure out what gear ratio to run