GM 7-5/8" Diff help?

I've got a Challenge-friendly project on the go, and need some help.

I have an GM 7-5/8" axle, out of an '88 Firebird 305TBI/Auto. I think the gearing is somewhere between high and suck. What can I find for cheap in lower gears and/or LSD out of the wreckers?

Thanks.

G

My 1998 Camaro Z28 6-speed came with a 7 5/8" diff and a Positraction. Later Z28s had a Torsen. You'll want to check on the spline count of the diff, mine was 28. I THINK the ratio is a 3.72.

are you positive it's a 7 .625? if it has disc brakes and a goofy looking cover, then it's a Borg Warner 9 bolt..

S10 trucks would be the best place to find deeper gears for a 7.5/7.625- 4 cylinders sometimes had 4.10 gears.

the 85-88 Monte Carlo SS had 3.73 gears, but i think they stayed with the 7.5 and never got the 7.625. Astro vans had a 7.625 rear- i know the AWD models had 3.42 gears, but maybe the cargo vans had 3.73 or 4.10 gears.

i guess the moral of all this is to learn what vehicles got that rear end and how to decipher the RPO codes when scouring the junkyards..

What does a "goofy looking cover" look like?

My Camaro diff is now happily inside an S10 housing, so they're both the same.

according to the third gen.org web forum, the 88 firebird with a 305 and auto trans came with a 2.77 ratio. doesnt say whether it is lsd or open. i'd say this is squarely between high and suck.....

It has "7-5/8" stamped on the pinion.

It has 26 spline axles.

I looked up www.thirdgen.org and it says I have 2.73 .

Can I just plunk any 26 spline diff and gears in the housing, or are the housings unique?

It's very definitely an open diff, and very definitely suck.

SkinnyG wrote: It has "7-5/8" stamped on the pinion. It has 26 spline axles. I looked up www.thirdgen.org and it says I have 2.73 . Can I just plunk any 26 spline diff and gears in the housing, or are the housings unique?

"Plunk" is not really the word I'd use, unless "Whiiine" is what you want to listen to for the rest of your days.