crazyblue92

i have a 9 bolt chevy rear end i got it from a guy who claimed it came out of a 80's I-Roc but i want to know for shure this guys has so many car parts laying around i need more proof than just his word. how do i know i have the numbers off the ring gear i didnt know if that would help me of not.
The numbers are 1252065 17 41 11 77 R
I plan on rebulding the rear end with new seals and stuff thats why im so anxious to find out.

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iTrader: (14)

what do you want to know? if its for a 3rd gen? or if it was origionally under an iroc?

crazyblue92

i want to know what it is. it doesnt have the same yoke on the end as my original 71 had in it and if i go to find a re build kit for it do i just say "i need a 9 bolt Chevy rear end rebuild kit" ?

AlkyIROC

If there are 9 bolts on the rear cover with a rubber fill plug in the cover then it's a 9 bolt. They were only available in third gens and only from 87-89. On the bottom of the housing there should be BW or Borg Warner cast into it.

None of those numbers translate to a gear ratio that the 9 bolts came with. Best guess is 41/11 which would be 3.73 gears. Count the teeth on the ring and pinion. 9 bolt diffs got ratios that the 10 bolts didn't get. 9 bolts came with 2.77, 3.27, 3.42. The 3.70 ratio was an over the counter set from GM. If it is a 9 bolt then someone has replaced the factory gears with aftermarket ones.

You need a 9 bolt Borg Warner rebuild kit for a Camaro/Firebird built from 87-89. GM didn't make the 9 bolt diffs.

Your 71's yoke will be completely different. Third gens use a 3R u-joint.

samiam91RS

but not 3.42 its actually 3.45 thats what i ended up with, like he said, count the teeth on the ring and pinion and divide them and you get your number, also mine was stamped on the side of the ring gear just take a rag and wipe you should see it. good luck getting that old fill hole plug off, mine was so worn and old it just ccracked off. get a new one ahead of time im tellin ya. one of those screw in types.

good luck