How can you tell what gear ratio you have by looking?
And then what was stock on a '91 RS?

 

Neo, Look in the glove box between the seats. There should be a code GU and a number. I'm pretty sure these are the codes:
GU2 = 2.73
GU4 = 3.23
GU5 = 3.42
GU6 = 3.73
I don't know what the stock gear was.

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91 Formula WS6
Home Made Ram Air,K&N Air Filter,Air Foil,
Ported Plenum,Underdrive Crank Pulley, Crane AFPR, Edelbrock High Flow TPI Runers, Holley 19lb Fuel Injectors, SLP Headers, SLP Y Pipe & Complete SLP 3" Exhaust and Muffler, High Flow Cat, Mobil 1 Oil, Hotchkis STB, Spohn LCA's and Panhard Bar and other polyurethane goodies.

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Add your 91 F-Body to my 91 F-body's Links page, or be added to my F-Body Links Page.

 

91 RS with a TBI, automatic trans has an open 2.73 gear, 5-speed is an open 3.08 gear. For 6-cyls, I dont know.

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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=-

 

There's also an axle ID number stamped on the "front" of the passenger side axle tube. It'll take some soap, wire brushing and a wet sponge to see the #'s, if they haven't rusted away already. It's a long code, three letters of which are the ratio and posi info. The Haynes 82-92 Camaro/Firebird manual lists these codes for all years. The GM service manual lists the codes only for the year the GM book covers. If you don't have either book, and can't find the RPO code sheet, put that code # up here and we can try to look it up.



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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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I have the GU5 code on my 85Z LG4 5 speed. Does this mean I have 3.42 gears or are the codes different for different years. I had thought that LG4 5 speeds came with 3.08 rear ends. If anybody has any ideas let me know. Thanks

 

Ron, just a little off:

GU2 = 2.73
GU4 = 3.08
GU5 = 3.23
GU6 = 3.42

Troy, you've got 3.23's and thats perfectly normal for carb'd cars.

 

Thanks for the help!!

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Current: 1991 RS 305 TBI
Past: 1990 RS 305 TBI (A woman forgot what red lights are for)
Current: mostly stock - newer 305 w/ 12,000 on it
Eclipse speakers all around w/ 10" tube in back
Future: 2" Cowl hood w/ K&N filter