What kind of rear do I have on a stock 90-305-TPI Formula,WS6 w/5/speed? I bought the car at a dealers auction. The bird was near mint w/120K. She has an aluminum drive shaft.Looks like it's been there for a while.Disk brakes appear to be non 2 piston type.Could the car be rare?
Thanks in advance
Mike

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90 Formula-WS6-TPI-305/5 speed. Slightly worked.

 

Do you have dual cats or a single cat? If you have a single cat, then you have a 10-bolt 3.08 rear end. If you have dual cats, then count the bolts on the differential. If its 9, you have a 9-bolt 3.45 rear end. If its 10, you have a 10-bolt 3.42 rear end.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Thanks for the info. I have dual cats w/9 bolts but I also have what apears to be a stock(from dealer) aluminum drive shaft. I wish I could get the RPOs for my car but it has beeen re-painted, original color(maroon) and there are no stickers of any kind left. I know it's not a 1LE car but all this options difference got me intrigued.I was surprised to find out that my friend's, leather w/all options 89 TA, is a TBI w/drum brakes.I figured that if you got a full out Trans AM, you would get the TPI/4WDB package.
Did formulas come w/similar deals? This "options" business has me buggin'
Please help.

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90 Formula-WS6-TPI-305/5 speed. Slightly worked.

 

ok .. in 1989 they stopped installing the 9bolt borg warner rearend in the f-bodys. so you have to have the 10 bolt 3.42. and that is a great rearend to have. i wish i had one but they were only offered in the 5spd option, and i missed that option i wanted the 350 instead of that little 305. no offense. i just like the power more. have fun man. keep it clean it will be worth something some day. all f-bodies will.

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1990 IROC-Z L98 350 TPI
AFPR 49PSI, GUTTED AIR BOXES, K&N, RAM AIR, PORTED PLENUM, B&M SHIFTER, 3.23 LIMITED SLIP, DUAL CATS, STOCK SUPER TURBO EXHAUST, COOPER COBRA XST's

MUSTANGS...ONLY 4 LUGS....HAHA THAT IS HILARIOUS.

 

Actually they stoped making them in 90. 89 was the last year.