[scuzz]

Can anyone tell me how many splines are on the oem 8.5 & 8.6 rear ends. I hear 28 in some places and 30 in another.
I don't know and can't find it. I know someone here is sitting on correct answer.
Thanks guys,
Ron

 

[goes2fast]

I think it depends on year and application the newer ones are 30 spline I think but I'm no expert. There are others on here that know more specifics than I do but if you are doing a V8 swap you definitely want 30.

 

[big gear head]

As far as I know all 8.5 and 8.6 GM corporate rear ends had 30 spline axles after '90. The S series 8.5 might have been an exception. The 8.5 was upgraded to 8.6 in '99 and all of them should have 30 spline axles.

 

[dime-dozen]

you are correct 28,30
was typing this as BGH did.

 

[67Truckin]

If I recall correctly my son's 1994 ZR2 pickup had 28 splines on his 8.5" rear axle.

 

[oldeerslayer]

The only replacements I can find for 94-97 ZR2 list them as 30.

AXG26027706

Just Differentials, Justdifferentials.com, JT Parts, JT's Parts & Accessories is a leading distributor in differential and axle parts from Nitro Gear & Axle, Nitro Gears are available for all types of vehicles.

www.justdifferentials.com

GM 8.5" Axle Shaft 94-97 S-10 ZR2 30 Spline 29-1/8" 5 Lug Rear – www.RigidAxle.com

Axle Shafts by Nitro Gear & Axle Description Our OE replacement axles are made of forged alloy for a 20-30 percent increase in strength over their stock counterparts. Nitro chromoly axles are also precision machined and heat treated but are designed with extra material for strength where it is...

www.rigidaxle.com

 

[scuzz]

I just bought 3:42 from 99 Blazer 2dr, 4.3, 5 spd. RPO tag didn't say G80 though. I'm going to try to pull cover tomorrow, and see if I'm going to have to buy posi or not. I'll count while I'm there and make sure what it is. Buy of century though, 100.00. I guess it being 5 spd v6 made it 8.5.

 

[goes2fast]

I just bought 3:42 from 99 Blazer 2dr, 4.3, 5 spd. RPO tag didn't say G80 though. I'm going to try to pull cover tomorrow, and see if I'm going to have to buy posi or not. I'll count while I'm there and make sure what it is. Buy of century though, 100.00. I guess it being 5 spd v6 made it 8.5.

Just don't waste your money on a Gov maybe it will lock, get a good aftermarket diff like a Detroit locker, TruTrac, or Eaton.

 

[dime-dozen]

should be an 8.6
post pics in this thread

8.5/8.6 owners weigh in please

just an update we are headless chickens with storm prep gonna be a week if we dont wash or blow away No problem.....stay safe !!!!

www.s10forum.com

 

[MY S10]

I just bought 3:42 from 99 Blazer 2dr, 4.3, 5 spd. RPO tag didn't say G80 though. I'm going to try to pull cover tomorrow, and see if I'm going to have to buy posi or not. I'll count while I'm there and make sure what it is. Buy of century though, 100.00. I guess it being 5 spd v6 made it 8.5.

Sent you a text message.
Thanks, David