what rear do i got??

[justlearning]

okay i got the rear end out of an 87 iroc w/ positraction and disc brakes can any one tell me real quick what rear it is. its got the tag still on it but its at a shop, but i found out it did brake teath and im gonna go ahead and get all new shit, ring and pinion, in/outter pinion bearings, shim kit, and probably a carier cause i havent looked yet but id say mines shreaded. i need to know what rear end i have like the bolt patter and is it a 7.5 or what i have no clue w/ out lookin at it and as i said its not here. the guy who is gonna fix it for me said he gets a discount from a dealership but id say i can get better ones from the same price on summit or jegs. if someone would like to throw togather a little combo for me then that would be great but just knowin what ive got would be a big help

[cooltc2004]

I believe its a 3.23

[justlearning]

yeah thats the gears i got i needed to know if it was like a ten bolt and like a 7.5 or 7.625 or what but im almost possitive thats the gears it had in it

[Savage Messiah]

10 bolt yes, and usually they say 7.5/7.625...

[89IROC&RS]

if its a 10 bolt rear end, it has a 7.5 or 7.625in ring gear, its the same monster and is interchangeable. If you have a 9 bolt rear, its a 7.75in ring gear. If you have rear disk brakes, im inclined to say you have the 9 bolt with a 7.75in ring gear. but the only way to know is to count the number of bolts on the diff cover.

[black84z28]

Originally Posted by 89IROC&RS

if its a 10 bolt rear end, it has a 7.5 or 7.625in ring gear, its the same monster and is interchangeable. If you have a 9 bolt rear, its a 7.75in ring gear. If you have rear disk brakes, im inclined to say you have the 9 bolt with a 7.75in ring gear. but the only way to know is to count the number of bolts on the diff cover.

the irocz's got 9 bolts..do some searching over at thirdgen.org and you can find a few places that carry gears and rebuild kits for that rear

[Savage Messiah]

actually the 12 bolt, 10 bolt, etc is based off of the number of bolts on the ring gear/differential from wht I understand (what John told me a while ago), dunno if they change the diff cover and housing for the different differentials.

[cooltc2004]

I didnt read your post right, my apologies.

[89IROC&RS]

Not all IROC's got 9 bolt rear ends, it was an option and a rare one at that.

12 bolt, 10 bolt, and 9 bolt names come from the number of bolts that secure the diff cover on, not the number of bolts on the ring gear. Larger numbers of cover bolts indicate a larger housing, which naturally means a larger ring gear inside.

as far as a place to get parts for the 9 bolt rear end, check out www.9bolt.com, the guy has been more than helpful to me regarding information and is also one of the only places i have found for parts aside from the local junk yard.

[justlearning]

k guys i got the car back at the house today and it has ten bolts i counted and unless im just dumb it is ten bolt...and i pulled some numbers off of it if they would help they r 22522878 i belive and some other random stampings i got r12 and m23. but on that first set the seven may not be right im pretty sure it is but its hard to make out under all that grime

[justlearning]

okay and ive been looking on summit cause the dealership quoted some outrageous prices, but i found some gears a deluxe install kit, a differential cover, and a posi unit...my question is if i do need to replace my posi unit how do i know what spline to get. is it right as long as it matches up w/ the series like they have series two and three for ring and pinions and for posi units. also what about if my posi unit dosent need replaced if i get lucky what is the stock one, so i know what ring and pinion to get cause the dealership quoted me like 720 just for the ring and pinion if nothin else ill get those from summit they would be just as strong wouldnt they if i got like richmond gears or something along those lines?? please help!!

[89IROC&RS]

ok, the numbers on the housing can be decoded, but i dont know off the top of my head. What you want to look at is the spid label in the glove box. If you have a posi, youll have the code G80, then look for the code GUX, where X is a number like 4 or 3 or 2. I dont know the direct representation, but i believe that a 3.23 is a GU3. If you do indeed have a 3.23 gear ratio, you have a three seriese carrier. a two seriese is 3.08 and numerically lower gears. a three seriese is everything numerically higher than 3.08. Also, all ten bolt rear ends up to 89 were 26 spline, it was in 89 that chevy changed to the 28 spline axles. A way to verify is to pull an axle shaft and count the splines yourself.

[justlearning]

well thats just it i have a 91 rs and im pretty sure i put it in out of an 87 iroc... so the decoding thing is probably out but those r the numbers i got from the bottom of the stump and im sure its posi and has disc brakes.