I got under my car today to see if i could figure out what kind of muffler i have (its been buggin me) and i saw i had a 10-bolt rear. on it was some number...
GM 10
2522878 or maybe 676 (instead of 878)
what does this number mean? also...w/o jackin up my car and doin the driveshaft/tire thing, how can i tell what rear ratio i have. a sticker somewhere? its a 92 so no glovebox.

 

look in the back hatch compartment. drivers side should have a little cubby type deal. you have to open it with your door key. RPO codes SHOULD be in there. if not you have to do the jck thing.

 

That number is probably just a part number. Or, if it was a metal tag on the cover held on by a bolt its an ID tag.

No glove box! Imagine that The RPO sheet is usually found under the CONSOLE lid.