I got a chance to buy a rear out of a S-10.For my 74 Omega. 3.73 gears posi , I guess it's a locker?For $300.I know it will take some work to make it fit,but does anyone know if it will hold up?Any input would be helpful.
railguy

 

You can use the carrier & gear set from the S-10 & put them in your original housing. They are both 8.5" differentials. Making the S-10 housing fit into the Omega will be a huge PITA.

 

Yea it's definitely a winter project.....all winter.But where I live I got 7 months easy.Are you sure it will fit I don't know much about rears.
railguy

 

s10 is 7.5 74 omega is 8.5 dont think you can just swap carriers. depending on what you have for power,for a street car thats not neutral dropped,it should hold up.

 

an s10 zr2 i believe is 8.5 but 6 bolt wheels

 

You are correct. My post above was incomplete. Only the ZR2 optioned trucks have the 8.5" diff. If it is a a base 7.5" unit walk away.

 

I guess I'll forget about the S10 rear.
I know a guy who has a posi "carrier"? out of a Grand national that suppose to fit dose anyone know any thing about those?Not sure of the year but it was bought for a 74 Omega.He couldn't find the spring that goes in it so he bought another unit,now he knows where to get the spring.I'm trading him some parts for it.I have a 74 rear that I'm taking with me when I go to swope with him.I'll check to make sure it fits before we complete the deal.Can anyone tell me anything to look for.There are 3.42 gears that go with it.
railguy
'

 

The GN posi is the same 8.5" carrier and 28 spline axle as your Omega. The S-10 carrier would be 30 spline so you would have to buy new axles using the S-10 unit.

 

I have a 74 Apollo rear I took apart and I thought it was 26 splines.I guess I'll double check today.Maybe I should just take mine apart some time.Winter's just about here 36 degrees this morning.
railguy

 

Your right 28 splines.So if it's 30 splines on the pinion ,28 on the axles and 8.5 inch ring should it fit or what are the odds.
railguy

 

The Turbo 3.8 GN G body Posi Unit and 3.42 gears for that matter (8.5 28 spl) is a direct fit to your 74 X body (8.5 28 sp) and forget the S10 idea as 99.9% of S10 are little 7.5 in both 26/28 spline and it would be a Gov-Lock POS style "Gov-Bomb" not a regular Posi like the 8.5 car. , very few S10 Zr2 4x4 around for parts and also the very very rare 2wd 4.3 V6 5 speed S10 8.5 rear are around. No such thing as a 6 lug S10, thats 1/2 ton truck talk. The Zr2 8.5 S10 rearends besides being 8.5 ring gear and 30 spline are just a wider track than the regular S10 .. If you wanted to buy new alloy Mosier or equivelant 30 spline C clip style stock length axles for your Omega then you open up to easy to find 30 spline 8.5 Auburn style Posi units out of 90's Impala SS, Caprice , Buick Roadmaster cars, wagons, taxi, police.. My dad has a 92 ish Roadmaster wagon that is a 3.23 Posi. so thats a great source for both gears and Posi on a budget.

 

Ack. It's still in the mid-90s here.

 

Put a ford 9" in it! Although since you have a corporate 8.5" you could grab a new carrier and gears and install it in your housing with one of those diff covers that help keep the carrier caps bolted down to the housing. I have seen 10 bolt diffs hold up to a lot of abuse at the track. My main reason for going with the ford 9 is because I have a friend with a jig to narrow the housing, and i already had half the parts I needed to install it. at the end of the day I probably have 1k into my rear axle but its a 4.11 detroit locker its 2" narrower than stock, and it has S10 blazer rear disc brakes mounted on it. ( something else you can look into is installing S10 blazer/pickup disc brakes onto a corporate 10 bolt housing, its not that hard )