Originally Posted by cobalt327
I don't know of any 5-plus ratio ring gear/pinions that are made for a 3-series carrier (4.88 is about the steepest for a 3-series) so you might look up the casting number to see if the housing is a 4- or 3-series.
Still best to count the teeth- that way you can see if it's a posi, the condition of the teeth can be seen, etc.
A word of caution: Be sure to use a W I D E pan to catch the diff lube! It stinks to high hell, and if you get it on the floor of the shop or driveway (let alone on you or your clothes), you'll regret it.
I might be wrong but in a 12 bolt diff, I think you could get into the 5's and even 6's...The 10 bolt was the one that the 4.88 was the steepest...like I said I could be wrong but, something just jogged my memory.
Oh, and if you spill gear oil on your clothes and your married and you bring it home to your wife to wash...in most states that's grounds for divorce.