I like to think I know a lot about third gens since I have been in one since I knew how to drive, but the car I have now puzzles me. I think my 90 Formula 350 is a WS"7"(not WS6). It has the performance suspension and it came with 16" wheels, but no rear disc brakes. Also, it doesnt have a limited slip rear end, since one tire will spin when I do a burnout. I had no clue GM even offered an open rear end option on a Formula in 90. Am I wrong about any of this? Any info on this car would be appreciated. Thanks.

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350 TPI, K&N filter, Moroso cam, Airfoil, Accel fuel pressure regulator and gauge, Hooker headers, Flowmaster 3" catback ...more to come.

 

Check your RPO codes for G80. Thats the GM code for positraction. Also check for J65, which is the code for 4-wheel disc brakes. Your RPO code sheet will be either in your glove box between the seats, or in your rear locking storange compartment. You might have a posi rear, but its worn out, making it act like an open rear. I am 99.9% sure that all 350 TPI cars came with positraction.

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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=-

 

I would agree with the 99.9% as Kevin says. All the literature from GM indicates the L98 came with positraction BUT GM can (and does) make changes from their advertising.

As an example, ALL GM literature on the GTA L98s in 1991 state that they come with 4 wheel disk brakes. My car came with aluminum rear drums, not 4 wheel disk brakes.

So as Kevin said, the only way to tell for sure what came stock on your car is by checking the RPO codes.