Brycegibler

Hey third gen I am going to put in new gears in my diff but need to know the stock ring gear measurements. I was thinking it is 8.5 in. but need to be positive before I purchase the wrong part. Thanks in advance.

Night rider327

iTrader: (13)

7.625" (7-5/8")

8.5" is a much bigger/strong rear end used in the second gen F bodies and 80's full size trucks along with many others.

The third gen F body got the 7.5" in 1982 and then in 1986 it was upgraded to 7.625" with 26 spline axles, then in 91 got 28 spline axles with same 7.625" ring gear and stayed that away all the way through the 2002 F body

Brycegibler

Okay thank you. And would you say it's best to stick with the 7.625?

Night rider327

iTrader: (13)

You have to stick with 7.625", your housing will not fit anything larger. If your meaning between 7.5 and 7.625", yes stay with 7.625". The size in this case means strength and bigger is better.

Ever hear gear heads/hot rodders talking about a ford 9"... Well 9" is the dia. of the ring gear. Much bigger, much stronger than the 7.625"

Brycegibler

Yeah I'm going to stick with 7.5 auburn and get 3.73 gear ratio stock is the 2.72 or 2.73 I don't remember but I'm going to go with the 3.73.

big gear head

Do you already have an Auburn or are you thinking of getting a new one? If you don't have one then I don't recommend getting one. There are much better differentials out there. The Eaton Posi, Eaton Truetrac, Yukon Dura Grip and the Power Trax Grip LS are all better than the Auburn.


Your '92 should have the 7 5/8 rear end with 28 spline axles. You need to be sure that the gears you get match the series of differential that you have or are going to get.

Brycegibler

No I don't have anything yet and a third ten member told me stock 92 Trans am auto 5.0 has the 2.73 is that wrong? And your saying I can't swap it?

big gear head

Yes, you can swap it. You just have to be sure that the parts work together. You can't put a 2 series gear on a 3 series differential. Be sure that you get the correct gear and differential so that they will work together. 3.08 to 2.14 gears use a 2 series and 3.23 to 4.56 use a 3 series. You can get thick 3.23 to 4.56 gears that fit a 2 series, so be careful how you order your parts.

Brycegibler

Okay thanks and I was just gonna get a 3.73 kit that has the ring and piņon and posi and all bearings

big gear head

In that case everything should match fine. If you are ebay shopping then I would recommend contacting ebay seller monzaz and see what he has to offer. He was my partner in the parts business for several years and should give you a good deal.

Brycegibler

Alright thank you