I'm going to be replacing the rear end on a 96 blazer 2 door 4x4. What kind of rear end will fit? And are there different gearings in this same year that I should be aware of?

 

Look in your glove box at the RPO sticker and look for one of the following codes:


2.73 = GU2
3.08 = GU4
3.42 = GU6
3.73 = GT4, GQ1
4.10 = GT5

That will tell you your gear ratio. You need one from a truck with the matching code.

Also, if you find one with a G80 code, it also has a factory installed "gov-lock" locker, which will give you alot more traction.
As long as it comes out of a second gen 4x4 s10 pickup, blazer, jimmy, or even bravada I believe, it will fit.

If I were you I would search for a disc brake rear(I believe these became standard in 98) that is a g80

 

Hey thank you for the info. Is there any way to check what diff it is with the VIN number? And if it's a ZR2 or not?

Cheers

 

If you call a Chevy dealership with the VIN they may be able to help you out, other than that I don't think there's any way to check by VIN.

If it was a zr2, one of the RPO codes in the glove box would be 'zr2' aside from that, it should be fairly obvious, they have fender flares, sit 2.5 inches higher, have a wider stance, and usually (unless someone downsized) have 31" tires. As well as a zr2 decal on the quarter panels.

Now would be a good time to note that the ZR2 package has a wider rear end and will not interchange with the other 4x4s

 

Hey so it has the GU6 3.42 rear end with the G80 locker. Any 3.42 rear end should fit regardless of the G80 locker correct?

 

As long as it's from another 4x4 yes. however I would recommend finding another one with the g80, just because of the added traction-but it is not necessary

 

And if it's a ZR2 or not?

Zr2's came with the 8.5 10 bolt rear and they are approximately 4" wider than a Blazer 4x4 rear axle, no spacers for Vette,Camaro wheels if you are considering that. I will be doing this swap in the future after rebuilding both differentials and installing a Tru-Trac in place of the G-80.

 

While you are correct that the ZR2 axle is wider than the normal S-series 4x4 axle (4" wider) it is incorrect that they are not compatible. The spring perches are exactly the same, and many people have swapped in a ZR2 axle specifically because they want to improve the factory narrow rear stance. In my opinion it is a viable option, as long as one understands that it will be wider

If his truck has 3.42 gears it is almost certainly not a ZR2. The ZR2s came factory with 3.73 gears, and the previous owner would have had to change them to a different ratio. S-series trucks with 3.42 gears and 31" tall tires (factory on ZR2) significantly lack low end torque, and I am certain that it would not be a factory option.

 

Now would be a good time to note that the ZR2 package has a wider rear end and will not interchange with the other 4x4s[/QUOTE]
I got a ZR2 axle from a 2 door Blazer for my 4 door. The only thing that is not a direct swap is the rear sway bar. I will need to use the original one and it's mounts to the axle. The exception is the front axle CV shafts and A arms that are a different length on ZR2's