What posi-trac rear end would be ideal on 92 firebrid


Asked by Jan 22, 2014 at 06:47 PM about the 1992 Pontiac Firebird Base

Question type: General

rebuilt 305 engine, eventually looking to put in a built carbureted 350 or 355, starting to buy parts to rebuild chassis and suspension of car, what gear/type of posi rear end would be ideal?

3 Answers


What most people put in is a ford 9".

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3.73 i got my new diff from auburn gear,best quality and a very reasonable price


Your car came with the 7.75 inch axle and was available with 2:77, 3.27 gears. The earlier ('87-'90) 3.45 will also bolt in. Be careful in that the available stock 3:45 gears will only fit the 7.625" axles. Auburn or Yukon posi is the best deal going, easy bolt in, and available in lots of ratios. You'll need to make a few decisions before selecting the ratio: 4 speed, 5 speed, manual, auto trans? How are you driving the car - mild street race, or all out, or a little of both? If you want decent gas mileage and wicked performance, you'll want some kind of overdrive trans, and that's going to determine the rear gear ratio. My point is, you can go with a stiff set of posi gears if you have overdrive, otherwise I would not go past the 3.27 with your engine. Good luck, the 92 is a great platform.

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