QUESTION about '97 1500 rearend?

aero_ub · June 16, 2004

Hi guys,

My brother has a '97 Vortec 350 1500 Chevy. It is 4x4 and acording to the RPO codes has an OPEN carrier (not posi) and 3.42 gears.

We want to put in a Posi carrier and 3.73's in the rear.

FIRST, there is a problem doing it to just the rear and not the front even though it has 4WD right?

Second, I had him going out and count the bolts on the rearend and it is a 10-bolt. Now I know a lot about the S-10 rears (7-5/8), but I would assume that this must be the 8-1/2" rear since it is still a 10 bolt? Is this without a doubt an 8-1/2 if it is a 10-bolt? I would think any of the 4x4 1/2 tons would have gotten a 7-5/8!

Third, What year carrier and carrier/gears would work in his 8-1/2? I've seen gears and carriers listed on ebay as 8-1/2 but say that it is for 99-03? Wouldn't these still work on the '97 rears, or did something change?

Fourth, Would his axles be 30 spline? That is what I see all the newer 8-1/2 carriers listed as but just want to double check...I know on the s-10's they have 28 slpine.

I know the camaro's and S-10, but need a lesson on the fullsize trucks!

Thanks you very much for any info!

Ken

aero_ub · June 17, 2004

I know someone here must knowthese things?

Cool Zr2 · June 17, 2004

We want to put in a Posi carrier and 3.73's in the rear.

So your going to only run 3.73's in the rear? LMAO, I want to be there the first time you put it into 4x4, its gonna be funny.....

But seriousley, are you?

citydriver · June 17, 2004

We want to put in a Posi carrier and 3.73's in the rear. FIRST, there is a problem doing it to just the rear and not the front even though it has 4WD right?

BIG PROBLEM

1st time you try to move it in 4wd..The transfer case will explode

That being said,it could have a 8-1/2", 8-5/8" or even a 8-3/4"

Only way I know of to be sure is to pull the cover and take a look...IF you REALLY wanna do this may I suggest that you find a donor vehicle in a local salvage yard that has 3.73s and maybe even a locker and buy the front carrier assembly ALSO.

The axles from '88 thru '98 should work.....Just a thought

aero_ub · June 18, 2004

Yeah, I didn't think you could do that on a 4x4 but wanted to ask. There isn't anything wrong with having Posi in the rear and not the front though right?

He wants to at least get a posi carrier. Does anyone know for a fact that the SPLINE count on the axles are 30?

Are the 8.5's like the 7.5 rearends where the 7.5's and 7-5/8's are interchangable? It doesn't make much sence that there would be three different sizes all within 3/8" for the same year rearend???

From what I've read though, I do at least get the feeling that something changed after '98 and would need '98 or older.

redvett · June 18, 2004

Yeah, I didn't think you could do that on a 4x4 but wanted to ask. There isn't anything wrong with having Posi in the rear and not the front though right?

No GM vehicles have G80 Limited differental in the front its too dangerous along with trying to steering.

citydriver · June 18, 2004

There isn't anything wrong with having Posi in the rear and not the front though right?

No my '95 has the G80 locker in the rear,redvett is right about y they dont put them in the front.

From what I've read though, I do at least get the feeling that something changed after '98 and would need '98 or older.

GM changed the body-style in '99,I'm not sure how much they changed the drivetrain without looking

Are the 8.5's like the 7.5 rearends where the 7.5's and 7-5/8's are interchangable?

If I remember correctly,the 8 through 8.75 use the same carrier,but dont quote me on that,I could be wrong...and I'm not sure about the spline count either