I need a GM 8.5" 10 bolt rear that measures 54 1/4" form back plate to back plate. Anyone know what car's GM used this size rear in. I have some clues from the old rear.... Stamped on the on the r/s case is GM69 , on the left side of the case is 3969340NF. on the r/s tube is stamped O(I think, it's not very clear)then, OC 0706G1 I know that it's a 2:73 rear. Thanks, Joe
Outside Width Year Model 54.25 1983-2004 Chevy S10 2WD, GMC S15 2WD 57.75 1962-1964 Chevy II/Nova 57.75 1965-1967 Chevy II/Nova 58.00 1978-1988 Chevy Malibu, Monte Carlo 59.50 1968-1982 Corvette 60.00 1955-1964 Chevy Car 60.00 1967-1969 Camaro 60.25 1968-1979 Chevy II/Nova 60.50 1984-1995 Corvette 60.50 1964-1967 Chevelle 62.00 1955-1959 Chevy Pickup 62.50 1968-1972 Chevelle 62.50 1970-1981 Camaro/Firebird
Whats the width from Wheel Mounting Surface (WMS) to WMS? Backing plate measurements are erratic and misleading due to variations in brake shoe width requiring some backing plates to be countersunk more than others.
Have to second Hackerbilt, a backing plate to backing plate measurement will tell you nothing, if its roughly 58" from axle face to axle face, it's probably 79-85 G-body chevy. And pictures always help.
S-10's had the 10 bolt 7.5" rear ends I believe. They grenade easily under stress. Ask me how I know...
I need to find out how to measure. I thought I was doing it right. In the mean time a friend, has a friend that rebulids rears, mine has 2 missing teeth in one of the gears and the ring gear has some minor chips at the edges. So.... I'm going to get a price on a rebuild in the mean time.....Joe.
Takes the rear wheels off and measure from the wheel mounting surfaces. Pics will help, looking for cut off brackets etc. If it's on leaf springs measure the center of the leaf spring mounting pad, see if they look like factory mounting pads or added later on.
Nothing on this car is factory except the body.lol. From the ground up it's all retro.The chasis is even after market.
Understand, the rear end came from something, we will try to help you identify it. Could have been a G body with mounts cut off and leaf spring pads welded on, or a leaf spring rear with pads cut off and coil over mounts welded on. I've done it a few times. If you want to rebuild it, that's fine, gear, posi, bearings, it adds up. If you wanna see what it came from and try to find a replacement, we'll help.
indy is right on the mounts , a g body rear would have cast ears on the upper portion of the center section , and you could see if they were cut off , a leaf spring car would have signs of brackets near the end of the axle on the bottom side and the weld undercuts s or grind marks should show it also on the 8.5 there is a cast date on the center which would help to place what year range for decoding .
The 4.3 versions had a bigger rearend than the 7.5 and its pretty strong...and as Kevko says, apparently some even came with the 8.5.
I'd say you are looking at a mid 70's Nova / Camaro / Firebird rear axle. A good replacement would be far less expensive than having the gears replaced in yours. That's adding 3-1/2 to 4 inches a side for the mount surface to back of backing plate distance.
I get the GM69 from the case, on the ring gear itself I get o6 70, the tube is stamped O OC so I'm thinking it's from an Old's but I don't know shit...lol...A friend said it looks like it came off a G body. The leaf spring pads are welded on, but I don't see any sign of anything being ground down or cut off. I will double check that tomorrow. I'd don't know if only the broken gear could be replaced. I like most am strapped for cash, so, I'm looking to get out of this without being hammered to hard. Social security only goes so far..
What gear broke? That makes a difference. G body rear would have had those Mickey Mouse type big ears on top. Someone may have cut them off
4.3 S-10's with the ZR-2 option had 8.5", but they are wide. The other 4.3 S-10's had 8.2". The one I have is out of a '94 4x4 and is 54.5 inches wide backing plate to backing plate. Factory 3:73 with a locker. The outer axle bearings are the weak link.
I counted the teeth on the gears and it is a 2.73 10 bolt 8.5 inch. 54 1/4in backing plate to backing plate. A replacement rear needs to be the same size due to the off set of the rim's. We measured for a narrower one but there is no room, either tire would rub the frame or the fender.
one of the carrier gears, the one on the L/S side, it's missing 2 teeth, one just sheered off and the other was just ground up.
Spider gears- easy swap. Or cheaper yet Pull the pieces out and weld the spider gears together, Aka Lincoln locker No one measures and records a rear by backing plate- so you'll not get any help from that. You might get somewhere with the housing flange, but the most bestest way is wheel mounting surface to WMS. Pull the rear wheels and measure that. No ears or evidence of them then you can forget the G body thing. I'm with mr 48 chevy on probability
Pop the wheels off. Use two straight edges against the axle flange surfaces, one on either side, measure the distance between them. You need the measurement of the complete rearend assembly and axles, minus the lugs and the center rings that align the wheels. WMS to WMS.