Hey fellas
I need help and I know most of you guys will know this. I want to buy posi units for my 2000 blazer (front and back) and do not know what type of they are. I looked it up and I got conflicting info. They are either 7.2, 7.5/7.6, or 8.5 differentials. I am just swapping out the open end rears for limited slip posi's.

 

Easiest way, is to find a donor vehicle with "G80" on the RPO list in the glove box. 2 door and 4 door axle assemblies are the same. ZR2 is different and not interchangeable. Doubt you'll find a front limited slip, so you'll need the donor axle ratio to match your front axle ratio.


G80 is limited slip
GU6 is 3.42:1 ratio
GT4 is 3.73:1 ratio

 

If I was keeping mine I'd go with an Auburn Gear limited slip. $400 through Summit Racing but you will need to transfer the ring gear and do a complete setup which will end up costing a lot more if taken to a shop.
G80 complete axle is the quickest, easiest, cheapest way though.

 

I have heard that the rear end out of a 98-02 firebird or camaro can be swapped in as well. I could be wrong on that though.

 

In a 2wd, yes. Otherwise you would need to change out the gears in either the front or rear in a 4wd. Unless they are the same ratio in a F-body. I've been out of the loop with those for at least 10 years now so I can't remember what they came with from the factory.

 

I know some of them came with 3.42 and 3.73 gearing.

 

I been working on cars, trucks and motorcycles since the late 70's. My other project is a 1978 GMC Sierra 3+3 crew cab dually. I redid the 454 to a 496 and my other buddy did a total redo on the front and rear suspension. But do to medical issues, the friend let me have it for a song because I wasn't going to rip out the BBC and junk the rest of the truck. Instead of Auburn's, I was looking into Yukon's posi units. it is just a simple swap (if there is such a thing). just take out the open ends and put in the posi units, using OEM ring and pinion. Nothing major, even keeping the factory tire size and the factory rims. I just need the size of the pumpkin, thanks.

 

If you can't get the rpo code from the donor vehicle. Axle identification numbers are stamped on the right axle tube on the forward side. The first 3 digits are the axle ratio. The 7.6 and 8.5 have different covers. A google image search comparing yours against a zr2 (known 8.5) will identify yours. I put a Detroit truetrac in my 91 and loved it. I no longer needed 4wd to go through snow. Also, the ring gear bolts are left hand thread. Lefty tighty righty loosey. I broke one learning that.

 

Rusty Nuts, hello fellow Michiganian!

Okay, I'm going to breathe new life into this thread because I think it's a great area to explore. I took my jimmy to Belle Tire (a tire and "meh" mechanical chain in Michigan) the other day, and they told me a bunch of stuff that they think is wrong, among which was an axle that "might be going bad." I think they misdiagnosed it, because they do that about 50% of the time. Case-in-point, I complained about a front-end noise, and they told me it was probably a bad ball joint. When I went home and took the wheel off to check it out, I discovered that my sway bar link was GONE. No idea how they missed that. Anyway, I digress.

Although they may have misdiagnosed the axle, I still want to look into it and figure out what I want in case it does need to get replaced. My axle is a GU6. My question is, if you had an s10/s15 with a GU6 axle and could pick any axle to put on, what would it be? Caveat: the axle must be one which can be pulled whole from another vehicle and installed without modification directly to the car. Show your work or you receive no points for this assignment! :-p

 

Hello chevyman. Yes I'm proud of how well Michigan is represented by it's members in this forum.

I would forget everything that mecHACKnic told me. Not noticing the sway bar link is a big red flag. Since that was his possible cause for your front end noise are you asking about a front or rear differential? Did you replace the sway bar link? Is the noise still there? The GU6 denotes a 3:42 gear ratio only.