Car stock: 89 G92 Trans Am, 5.0tpi auto, 15" wheels, limited slip rear, rear drum brakes, single cat, 3" intermediate exaust pipe, PERFORMANCE SUSPENSION badge on dash, no engine oil cooler, t-tops... That's all I can think of right now. What I really wanna know is what gears I have, but I'm also wondering what other options I might have. Thanks a lot everyone. -Brian

 

Rear ratios for 89 as listed in the GM catalog are as follows:

Rear Ratio RPO Code

7.75" (9 bolt) 3.45 GM3
7.75" (9 bolt) 3.27 GW6
7.625 (10bolt) 2.73 GU2
7.625 (10bolt) 3.08 GU4
7.625 (10bolt) 3.42 GU6

RPO code is found under console lid.

 

Someone with more accurate info will have to back me up, but I'd be willing to bet the car doesn't have G92. Did you get the code G92 off the rpo sheet? If not then its not G92. G92 typically included the oil cooler. Someone should have the 89 Firebird sales documents and will be able to tell you what the standard equipment would be and what G92 included in that year.

 

G92 is listed as "Axle Rear, Performance Ratio (Merchandising Option)" This is a general RPO denoting an upgrade from the standard ratio, it is a general term & does not indicate a specific ratio.

 

I think you should have 3.27's.