I have a 89 Camaro RS that came stock with a 305tbi and a 700r4 tranny. I have heard that in 89 they put 373 gears in the rear end. I am in the middle of a 355 swap and now is a good time to put in replacement gears if they are not 373.... Does anyone know? Also I have read in certain tech articles that the 89 rearend was the best 3rd gen rear, anyone else know anything about that?

 

I know an 89 RS has a 2.73 open rear, I just put 3.73's with auburn limited slip in mine and there is a huge difference. The 355 helped also, I cant wait to go to TPI.

 

89 RS is an LO3. It's rated at 170HP @4400 255 torque @2400

1989 third gen with 305 and 700R4 tranny came with 2.73 gears only. No other options were available for that combination.

1989 was the first year of the larger rear disk brakes and the last year of the 26 spline axles. In 1990 they went to the larger 28 spline axles.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress

Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

 

Thanks for clearing that up. Now, on to jegs for the 373 gear setup. I just hope the stock TBI doesn't starve my 355 to death!!!

 

What is the difference between the 2 carrier #'s. I started looking and noticed 2 different ratio carriers, 3.08 and 3.23. How do I tell what I have?

 

No 89 car came with 3.73's from the factory. 2-series means your gears are 3.08 and lower. For our cars thats 2.73 and 3.08 are 2-series carriers. 3-series is 3.23, 3.42, 3.73.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
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