I have a 1990 Firebird with a 9 Bolt rear end. It did not come in the car and I am trying to identify what year 9 bolt it is and what cars it came in.

I was only able to find one casting number on the rear end diff housing. Here is a picture. I found the number P2808. I did not find numbers on the axle housing tubes.

9Bolt by jtwoods4, on Flickr

 

Year doesn't matter; there are no changes year-over-year in that rear in these cars, except that the last year (89) got decent brakes instead of the old cast-iron crap. So if it has that old garbage, it's 88-back; if it has the aluminum calipers, it's 89.

As far as cars, NO other car uses a rear that will fit these cars, so it's out of a Camaro or Firebird. No potential for any other origin. And since Camaro and Firebird are the same car with different sticker packages and sheet-metal wrinkles and cupholders, ... you do the math.

Don't bother with codes. It IS what it IS. LOOK AT THE PARTS THEMSELVES. You can learn EVERYTHING there is to know about it by catching up on the overdue "deferred maintenance", and making a point of actually looking at stuff while you're changing the fluid that DOUBTLESS needs changed.

 

Thank you for the response but there is still something that does not add up. They are not all the same because the 2.77 gear and the 3.08 gear CANNOT changed to a numerically higher gear and the 3.27 rear end CAN be change to a numerically higher gear (ex. 3.73) Which means something is different between the 2.77 9 bolts and the 3.27 9 bolts. If they were the same you could swap the parts between them.

I have the 3.27 gear in mine so what is unique about this rear end compared to the 2.77 version.

In the rebuild kits they mention a "4 pinion" setup and 2 or 3 series carries. What is different about these and how do you identify them.

 

The 3.08 and 2.77 gears fit a 2 series differential and all others fit a 3 series. There is no difference in the housing, only the differential. If you have a 3.27 gear then you have a 3 series differential.

All of these have a Borg Warner cone type limited slip differential with 4 pinion gears. That is the only limited slip differential that was ever offered in these rear ends. As I said above, the only difference is 2 series and 3 series.

 

Great! Do you know where I can get a service manual for this rear end? I am looking for specs for setting up this rear end.

 

Randy's Ring & Pinion has parts for it and they can probably tell you what the pinion bearing preload should be and what the torque specs are. 9bolt.com probably has this information on their web sight.

 

OK thank you.