I have 1980 cutlass that I just had 3.73 gears installed in its the 7.5" 10 bolt. My question is will the gears and carrier fit my new 86 Z28 TPI 305. If not what vehicles would I find these gears in at the scrap yard and how would I identify them I would also like it to be a posi, the gears in the car now are 2.73, they gotta go! Thanks

 

If your 86 has a 10-bolt, yes. You may have to change the head bearing on the pinion, somewhere around 80 they changed to a larger one. Use the install kit for the 86 and it will come with the right bearing.

As far as posi, you just need to get a 3-series posi carrier for 88-back. They started changing to the 28-spline axles in 89. Those axles are hard to find and expensive because there are relatively few cars that have them (low supply) and lots of people want them (high demand).