I have an '88 Camaro originally equiped with a 305 tbi and auto trans. I'm pretty sure that it has 2.73 gears. Does anyone know what size rear end this is? 8.5"?, 7.5"?, 7 5/8?". I also need to know the spline count, but I'm not sure if I need the count on the axles or the pinion? I want a posi unit but I want to use my stock housing. Thanks in advance.

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1988 Camaro Sport Coupe: Orignally: 305 TBI 700r4
Now: 1974 350CI, 2bolt,.030 over, Badger Flat Head Pistons w/ valve relief, Melling high performance street cam, GM Cast Vortec Heads, Edelbrock RPM Air Gap Intake, Edelbrock 600cfm w/ electric choke, GM HEI w/ vacuum advance, Weiand Low Profile Air Cleaner, Mallory 5 port Fuel Pressure Regulator, Mr. Gasket Throttle Cable Bracket, Corvette Shift Servo, 16" IROC Wheels, Every thing else is STOCK
Soon: 3.73 or 3.42, Gears, Hoosier Q/T

 

Most likely (if it's stock) it's a open 2.73, 7 5/8" ring gear, 26 spline axles.

 

I agree with the above post.
If you want to upgrade to 28-spline axles, you can use the Torsen take-off posi from SLP. It sells for $99...definately the best you can get for the money
Then you would just need to get the axles from an 89+ f-body. Last time I checked the junkyards were getting ~$25ea for axles.
As for gears, I reccommend Motive. I've installed 15+ sets, and have had no complaints (I do gear swaps on the side).