ok far as i can tell from what people here have been telling me i have a 3.23 gear in my 88 firebird. but.. wheni got the car on the rear end cover it had an 84 so i think that maybe they replaced the rear at sometime. i thnk this cause people have told me that 88 formulas like mine came witha 9 bolt.. so if i have a 10 bolt which yet i can count to at least 10 lol how do i tell if its an 8.5 or 7.5 or something other weird number that i dont understand! now that that is out of the way i know that i want a 3.73 gear but do i have a 2 series carrier or a 3? i am guess that i have a 3 series correct me if i am wrong. and i know from alll the posts that i want a power trax unit. right not i am unsure if i have an open end or posi again i am guess that i havea open end i am still trying to figue this out how to tell.. so with this said can anyone tell that i am mojorly confused here!! i know what i want just tell me what to do so i can get it thanks! sorry for being so stupid but transmisions on back i have no idea what i am talking about or anything so all the help the better i looked at power trax site but didnt find anything there to help me so u thanks guys for all the info i hope to get here thanks alot!!

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1988 firebird ws6 formula350tpi msd 6al box blaster 3 coil accel 8.8 race wires hooker shorty headers hooker cat back system pro shift light a pillar gauge pod and water temp and air/fuel ratio gauges autometer oil pressure gauge b&m mega console shifter, march underdrive pullies, tpis airfoil cvr high torque starter (love it)
best 1/4 mile run of 14.44@ 96.53
this run is before the new exhaust system

 

sorry couple things i forgot.also do i have 26 or 28 spline? and if i have the tag on my rear cover that means limited slip right sortof like posi is it? so if i have that will the power trax unit even work for me? i think the more i read the archives the more confused i get!! so i hope someone can clear this up for me!!!

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1988 firebird ws6 formula350tpi msd 6al box blaster 3 coil accel 8.8 race wires hooker shorty headers hooker cat back system pro shift light a pillar gauge pod and water temp and air/fuel ratio gauges autometer oil pressure gauge b&m mega console shifter, march underdrive pullies, tpis airfoil cvr high torque starter (love it)
best 1/4 mile run of 14.44@ 96.53
this run is before the new exhaust system

 

help me out here guys!!

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1988 firebird ws6 formula350tpi msd 6al box blaster 3 coil accel 8.8 race wires hooker shorty headers hooker cat back system pro shift light a pillar gauge pod and water temp and air/fuel ratio gauges autometer oil pressure gauge b&m mega console shifter, march underdrive pullies, tpis airfoil cvr high torque starter (love it)
best 1/4 mile run of 14.44@ 96.53
this run is before the new exhaust system

 

If you counted 10 bolts on the rear cover, you have a 10-bolt. It is either 7.5 or 7.625" (not much difference when getting parts for them).

Your best bet would be to get under there again and pull the rear cover off. Have a new gasket, drain pan, and a couple of quarts of gear lube ready before you start. Look at the large gear and count the teeth or look for a stamped number on it (like 41). Then look at the gear in the front and do the same (something like 13). Divide the larger by the smaller, and that's your gear ratio. If 3.08 or less, you have a 2-series carrier: If 3.23 or larger, you have a 3-series carrier. While you're in there, look inside the carrier for springs - if present, it's a posi; if not, it's open.

If it really is an '84 rear, it will be 26 spline.

I have "heard" that PowerTrax makes units for posi carriers, but I couldn't tell you for sure if they make them for 7.5's. Their phone # is 1-800-562-5377, call between 8-5 PST.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

If you have the 9 bolt it's probably a 3.27 ratio (ws6)

 

so how do i check the number for the spline? do i have do tear the axels out? so what are my options if its posi? anything?

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1988 firebird ws6 formula350tpi msd 6al box blaster 3 coil accel 8.8 race wires hooker shorty headers hooker cat back system pro shift light a pillar gauge pod and water temp and air/fuel ratio gauges autometer oil pressure gauge b&m mega console shifter, march underdrive pullies, tpis airfoil cvr high torque starter (love it)
best 1/4 mile run of 14.44@ 96.53
this run is before the new exhaust system

 

Short of pulling the axles out, there's no way to tell for sure because anything could have been changed out in the past.

One other possibility is to look for the 3-character code that is stamped on the front of the passenger side axle tube. Look that up in Haynes, which will tell you the original ratio, type (open, posi), and year. Unless it's an '88 or '89, the older years were 26 spline, the later 28.

Posi's can be rebuilt if yours is posi and isn't working properly. Or, replace the posi pieces with a PowerTrax if they make such a unit for 7.5/7.625" 10-bolt posi carriers.

[This message has been edited by five7kid (edited March 02, 2001).]

 

if i post what is stamped on the back could someone tell me what i am looking for? that would be great!! thanks

 

Go for it.

 

Geez... Jack one tire off the ground. Mark the d-shaft with a white piece of chalk so you can watch it turn. Rotate the free tire exactly one complete revolution. The driveshaft will have rotated oround the axle ratio, ie approx 3.5 driveshaft rotations for a 3.55 gear ratio, etc... no need to remove the diff cover to get axle ratio...

 

ok i will try that and let u guys know lol sorry this car is giving me fits! oh and if it has limited slip, can i get a power trax locker or is there something else i will need to do? thanks guys bear with me here i am new to this. 2 years ago at this time i had a hate to say it rustang and they are easy to get gears for 8.8 or 9 inch!! all this new **** is very confusing so please dont get mad at me for my ignorance! i am really trying to understand this stuff..

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1988 firebird ws6 formula350tpi msd 6al box blaster 3 coil accel 8.8 race wires hooker shorty headers hooker cat back system pro shift light a pillar gauge pod and water temp and air/fuel ratio gauges autometer oil pressure gauge b&m mega console shifter, march underdrive pullies, tpis airfoil cvr high torque starter (love it)
best 1/4 mile run of 14.44@ 96.53
this run is before the new exhaust system