I have a 90 formula firebird, with a Lo3 and a 5 speed, i know that my rear is a 3.08 open. How many splines are on my axles, and will a gm posi (#26036756) for 7 and 5/8 10bolt rear with 28 spline axles fit? any help will be greatly appreciated- i also plan on 373 gears.

 

28.

Yes.

Make sure that posi is for 3 series gears, life will then be good.

 

Your rear end is 7 5/8" which if you upgrade gears anytime you can look also under 7.5" as well as they are the same rear for all purposes.

And like RB said above 3 series

 

http://www.slponline.com/view_produc...TNUMBER=64501T

have you looked into this posi slp offers?

 

the link didn`t work for me but if it is the $99 takeout unit they are backordering them and you may not get one as I don`t know how you can backorder a takeoff part for a car that no longer exists

 

Supposedly they have some of the posi units themselves, there's some piece that goes with it (cross shaft maybe? I don't know) that's BO'ed.

At this point, I'd try to talk them into sending me the unit now, and then send along the other thing when it comes in.... since there will be no more of the posi units coming to them any more.

 

It's going to be a sad day in thirdgen mod history when SLP runs out of those take-offs.

 

are the slp units full posi, or a limited slip?

 

they are a torque biasing unit kind of hard to explain. Look around some though I find my posi and 3.42 gear from a member of the local f-body club I`m in and only paid $100 for both so now all I have to do is have them installed.