What rearends are in the Blazers?

Just like the title says.  I would like to know whats in mine but it would be nice to know whats in other ones. 
 
 
 
 

Rear Axle Identification
In your glove box you should have a list of RPO codes. Diff codes srart with a G
GT4

Rear Axle: 3.73 Ratio
GT5

Rear Axle: 4.10 Ratio
GU4

Rear Axle: 3.08 Ratio
GU6

Rear Axle: 3.42 Ratio
G67

Level Control: Automatic
G80

Rear Axle: Positraction

I actually ment what rear end as in 10 bolt, 12 bolt, etc. Im guessing its a 10 bolt but I dont know by looking and havent found it in the owners manual.

Good info though.

10 bolt, and if I remember right, it's a 7 5/8"

whats the preferred rear end? besides a nice blonde..  hehe

Depends what years but I think most 1st gens are using the same rear ends as the f bodies just different supension.

The ZR2 & Highrider suspensions (Chevy & GMC variants) has an 8.5" rear ring gear.  All others have the 7-5/8" ring gear.  And yes, they are the GM-corp 10 bolt.  The G80 locker is GMs Gov-loc arrangement and while it may be perfectly fine for on road to light offroad use, anything more and you'll want to put in a true posi or locker setup depending on your level of offroading.

quote:

ORIGINAL: swartlkk

The ZR2 & Highrider suspensions (Chevy & GMC variants) has an 8.5" rear ring gear.  All others have the 7-5/8" ring gear.  And yes, they are the GM-corp 10 bolt.  The G80 locker is GMs Gov-loc arrangement and while it may be perfectly fine for on road to light offroad use, anything more and you'll want to put in a true posi or locker setup depending on your level of offroading.

 
Got any suggestions on a good posi? Locker's are cool and all... but a posi rocks for 2wd slides, lol

quote:

ORIGINAL: drperry

quote:

ORIGINAL: swartlkk

The ZR2 & Highrider suspensions (Chevy & GMC variants) has an 8.5" rear ring gear.  All others have the 7-5/8" ring gear.  And yes, they are the GM-corp 10 bolt.  The G80 locker is GMs Gov-loc arrangement and while it may be perfectly fine for on road to light offroad use, anything more and you'll want to put in a true posi or locker setup depending on your level of offroading.

Got any suggestions on a good posi? Locker's are cool and all... but a posi rocks for 2wd slides, lol

Auburn makes good posi units, I used to run an air locker in my "strip/street" car, I am looking into the powertrax for the blazer, if you know how to use tools you can install it yourself in under an hour without touching the gears.

It all depends on if you have the G80 locker or not.  In an open case, everything can be installed without removing the carrier.  If you have the G80, I don't think anything goes into a G80 carrier...  So that means you'd need to find an open diff carrier and transfer over your gears, install new bearings, then install the posi/locker unit of your choice.

quote:

ORIGINAL: swartlkk

It all depends on if you have the G80 locker or not.  In an open case, everything can be installed without removing the carrier.  If you have the G80, I don't think anything goes into a G80 carrier...  So that means you'd need to find an open diff carrier and transfer over your gears, install new bearings, then install the posi/locker unit of your choice.

 
 
Bollocks! lol
I've got the G80 -_-

I am showing codes gt4, g67, and g80.

So I have 3.73, positraction, and the level control.

What is the level control?! The autoride?!

I thought that was ZW7, which I am showing in my glove box.


One last thing, the positraction diffs how do they work?! Gears or clutches? I will search for a diagram in the meantime.

Also what kind of synthetic diff fluid do you all run?! I will do my research on this, but I am just curious.

Rear End ID:
http://www.drivetrainspecialists.com/categories/gm/
RPO Codes:

http://www.fullsizechevy.com/forums/...ight=rpo+codes

Don't know if it still works for RPO Codes:

http://www.c2e.info/rpocodes/MODERNGMRPO.html
Aloha, Mark

Ths codes listed by Chevy Lover look to be for a Fullsize Blazer and not the S-Series Blazer.
I'll see if I can find the S-series version.
 
 
Edited. Try this version. Enter your codes and click check codes.
http://www.s10forum.com/rpo/index.php
 

Some non-ZR2's came with the 8.5" rear end actually.  Here's the one on the '98 blazer i bought to part out:



and here's one from a '97 ZR2:


 
and here's one from a '97 non-z blazer:
 


and here's the newer one on my '00 blazer ZR2:



The 8.5's have square tabs on the bottom of the diff, compared to the pointier tabs on the smaller rears, like in my brother's blazer:

Must've been a hidden factory option or something... Wonder how hard it'd be to swap out the axle/rear end... lol

Not that hard really... i've got one for sale if you want it
 
It even has a G80, disc brakes, and 3.42 gears... you'd be all set!  Between the 8.5" rear and the iron front diff you have, you'd be pretty well setup for lockers!

Thanks for the info on the 8.5" in non-ZR2 trucks. Are there any other ways to identify them? Like id dthey only come behind manual tranny trucks, or something like that? Is there a code in the glove box for them?

There's no code in the glovebox, but i do know that the squared off tabs are a dead indication.
 
Also, all 5spd blazers and S10's from 95 on (i believe, it might ahve been earlier) came with an iron front diff... so i wouldn't put it past GM to have included the 8.5" rear end in that unspoken package.

You may be onto something with the manual trans only thing Tim, a buddy had a 2003 s-10 with ZQ8 suspension, he ordered it with a manual trans and a 3.08 gear because it was the steepest gear ratio you could get that year with a manual trans.  So the day after he took delivery of it we ordered a 3.73:1 gearset for a 7 5/8" rear, and it turned out he had a 8.5" housing.  we never expected it at all, but a very welcome surprise of course.  My ex-father-in-law has a 1998 s-10 SS (yes a real B4U optioned truck) that he ordered with an automatic and a posi, and he has a 3.42:1 gear and a 7 5/8" rear end.  The CAR that I got my 8.5" posi out of for my Caprice was an olds, and when I was researching the ring gear size it DID have an option code for the 8.5" ring gear, it was GM8, but IDK if that is a valid code for the ST trucks.
 
EDIT......Hey Jigg, is that 8.5" G80 out of a 2-door or a 4-door?  If it comes with a manual only, it's have to be a 2-door of course, but aren't they different lengths?  IIRC, the 4-door's rear axle housing is a couple inches wider?

quote:

ORIGINAL: Jigg

Not that hard really... i've got one for sale if you want it

It even has a G80, disc brakes, and 3.42 gears... you'd be all set!  Between the 8.5" rear and the iron front diff you have, you'd be pretty well setup for lockers!

Really? I don't have no puny aluminum front diff? that's pretty spanky... that means an elecronic locker is a posibility! lol.

Do we know the size/specs of the front diff?  I think I'm going to have to take a look at my diff... Maybe I got lucky and got the 8.5"... Which would be really nice, as Auburn has a limited slip locker for the GM 8.5" 10 bolt rear end...

Though, the fact that you've got one sitting there with 3.42's is pretty swanky too, lol... Shipping would be killer, though...

Time to go take a picture of my diff! lol

Though, I suppose, to confirm the iron front diff, the only way is with a magnet? no special part numbers or anything, right? lol
 
Edit: Damn... I think I've only got the 7 5/8" diff...


Thumbnail Image

quote:

ORIGINAL: lastcoupe
EDIT......Hey Jigg, is that 8.5" G80 out of a 2-door or a 4-door?  If it comes with a manual only, it's have to be a 2-door of course, but aren't they different lengths?  IIRC, the 4-door's rear axle housing is a couple inches wider?

 
It was out of a 2dr.  I've never heard that the 4dr's are wider... can anyon confirm that?

The body might be wider, but I don't think the axles are... Not 100% sure on that, though...

Edit: from what I can find, the track width of the rear on the 4 door does appear to be a little bit larger... by an inch or less...
 
Only a ZR2 axle is wider, as far as I knew...

I'm pretty sure the body is the same width, but like I said I think the 4-door's axle is a little wider than the 2-door.  I'll do some research on it though.  How much you want for the axle Jigg?  Where is it located?

I run an auburn posi in mine and im lovin it! also 4:10 gears with 33 inch tires are perfect for a daily driver