ID Your Rear!

  

Ti28

General Motors Differential Axle Codes

What is my rear differential ratio?

Identifying Vehicles Equipped with OE Traction Adding Differentials

General Motors Production Options.

The most accurate method of determining a rear axle gear ratio is to look in the vehicle manufacturer's service manual.

The following Regular Production Option (RPO) codes identify the rear axle and transaxle overall final drive gear ratio's. These codes can be located on the RPO sticker in the glove box or in the trunk on most GM vehicles. These codes are arranged in alphanumeric order. Please refer to the information below.



The following figure presents differential cover/cover gasket shapes. Counting cover bolts and cover shapes is a common method to determine which ring gear diameter differential you have in your rear wheel drive vehicles.



When ordering Dana/Spicer Differential Parts provide bill of material number. This number is stamped on your right hand side axle tube. It's a number like 603XX-X, 604XX-X or 605XX-X. With this number you can tell exactly what components the factory used in the assembly of your differential. Plug the bill of material number in Dana's site, information is also provided should you want to change gear ratio.

  

98-S10-lifted

I dont see G80 on there anywhere unless Im just blind. If not, then the G80 is a "posi" rearend for anyone needing to know. I know that goes to for S10, Sonoma, Jimmy, and S10 Blazer, I dont know for any other models of truck.

  

Phildo

correct, you shouldn't see it on there. G80 isn't the gearing itself, it's the limited slip unit.

  

98-S10-lifted

Oh ok. I guess I should have read the thread a little better to see that its only about the ratio.

  

Diesel

It also Identifies the load housings as well as the axle final drive ratios.

  

98-S10-lifted

I guess I need to stop skimming through the threads and get all of my info straight.