Identifying an 8.5" S-series rear end.

ZZ4Blazer · 12-07-2004, 11:55 PM

Heres a few pictures I have taken of both my 8.5", and a 7.5" rear end out of a 2wd S-series.

Here are the differences, and easiest ways to tell between the 2.

As you should know, there are 2 main visual differences between the two.

First, here is a 7.5" rear end. Notice how the axle tubes are straight, and how the rear end cover is more square.

Close up of the axle tube.

Now, heres a picture of the 8.5". Notice how the cover is almost completely round, and the bugle in the axle tube just before it goes into the pumpkin.

Close up of the axle tube. Notice how the tube bulges right before it goes into the pumpkin.

A shot comparing the 8.5" cover (left) and the 7.5" cover(right).

Now, as I've said, most usually you'll have to have your driveshaft shortened going from a 7.5" to the 8.5" This picture should fully explain why. Looking at the flat surface where the cover would mount, notice how much taller the 8.5" is.

Hopefully that should explain the visual differences between the 7.5 and the 8.5", and how to identify one.

Catching Second · 12-08-2004, 02:15 AM

You're the man.

**LowKat** · 12-08-2004, 02:41 AM

Thanks for Rearends 101

Now I'm gonna be on the lookout

pimpinblazer89 · 12-08-2004, 08:09 AM

pics dont work

ZZ4Blazer · 12-08-2004, 10:29 AM

Somethings up with car domain. I had the same problem last night right after I posted them. I played with it for like 45 minutes trying to get them to show up, thinking I had something wrong with the link. Then, they just showed up and started working again.

Be patient, Im sure they'll show up here in a little bit. If not, I'll change it around.

slackware · 12-10-2004, 01:35 PM

I think the quickest way to spot a 8.5 is the small tabs on the bottom. Notice how the 7.5s are points and the 8.5s are square?

at least thats what I do

LT4BLAZER · 04-05-2006, 12:43 PM

I have one sitting around if anyone is interested!

**noob** · 07-27-2006, 10:54 AM

ok, so i got an 86 s-10 and im looking for a posi rear with disk brakes, or at least disk brakes...
ordred one from a 95 and it was wrong...but it wasnt even disk brakes, im pretty sure it was the 8.5"

but waht rear end will fit the 86 and be the same length
Thanks

LT4BLAZER · 07-27-2006, 07:16 PM

Quote:

Originally posted by noob
ok, so i got an 86 s-10 and im looking for a posi rear with disk brakes, or at least disk brakes...
ordred one from a 95 and it was wrong...but it wasnt even disk brakes, im pretty sure it was the 8.5"

but waht rear end will fit the 86 and be the same length
Thanks

Not sure I understand. Did you actually by one from a 95? I don't think they came with disc brakes unless you happen to get one from a Blazer. All the ones I have seen were drum brakes. Most of us have converted to rear disc by using late model f-body disc brake setup! Tube size going in to housing is the thing that is the easiest to determine 8.5.

daryla1933 · 11-14-2006, 11:05 PM

This was great info on the differences between the 7.5 and 8.5 rear. A detail that I need for my project: I've heard that there are different widths depending on whether you have an s10 pickup or blazer and whether it's 2 or 4 wheel drive. I'm looking for something that is: 1. 60" from wheel mounting to wheel mounting. 2. 8.5 ring gear. 3. 3.73 posi. 4. disc brakes. I don't think the zr2 option will work as the measurement is too wide, but maybe you guys have other info?

ZZ4Blazer · 11-15-2006, 06:03 AM

I believe that stock 2wd rear end is 54" wide drum to drum.

I also believe that stock 4wd is 58" drum to drum.

Blazer, truck, doesnt matter, 2wd is 2wd. Only differences between the width is 2wd, 4wd, or the ZR2 rear end.

I think your gonna be a little hard pressed to find an 8.5" that is exactly like your looking for. Would probably be easier to add posi and the gear ratio you want.

daryla1933 · 11-16-2006, 09:22 PM

Thanks for your input!

**billp** · 06-16-2009, 01:06 PM

S10 8.5 Zr2 Rears Are , I Believe, 65" Long.

Benalex · 07-13-2010, 06:30 AM

It was really a nice experience to read out from here because all the posts are interesting to read out and conating very useful information for the readers as well.

**6SpeedBlazer** · 07-13-2010, 03:49 PM

Quote:

Originally Posted by Benalex

It was really a nice experience to read out from here because all the posts are interesting to read out and conating very useful information for the readers as well.

die spammer

12-08-2004, 02:15 AM	#2
Catching Second Registered User Join Date: May 2003 Location: Charles Town, West Virginia Posts: 4,270 Ride: 1987 Blazer Seller Rating: (11)	You're the man. __________________ Pictures and a sound clip of my truck. "A true hotrodder wouldn't be content untill he had created a car so violent, so hairy, so totally sick that the very act of dropping the hammer would result in instant death. Anything less results in the need to go faster." - Tony DeFeo

12-08-2004, 08:09 AM	#4
pimpinblazer89 built not bought Join Date: May 2004 Location: Waterbury CT Posts: 2,797 Ride: 89 s Blazer 4x4 85olds98 Seller Rating: (1)	pics dont work __________________ Jeff 89 4x4 blazer slammed shaved 83 2wd blazer stock << frame for my 89 85 olds 98 daily driver http://www.cardomain.com/id/pimpinblazer89 AIM: pimpinblazer89

12-10-2004, 01:35 PM	#6
slackware gas assassin Join Date: Jan 2004 Location: Harrison Twp, MI Posts: 488 Ride: 85 v8 box Seller Rating: (0)	I think the quickest way to spot a 8.5 is the small tabs on the bottom. Notice how the 7.5s are points and the 8.5s are square? at least thats what I do __________________ 85 sbc blazer

04-05-2006, 12:43 PM	#7
LT4BLAZER Registered User Join Date: Feb 2004 Location: RED OAK TEXAS Posts: 8 Ride: 91 S-10 BLAZER Seller Rating: (0)	8.5" REAR DIFF FOR 2WD I have one sitting around if anyone is interested! __________________ 11.03@122MPH www.lt4blazer.net

07-27-2006, 10:54 AM	#8
noob Blazin Low Supporter Senior Member Join Date: Feb 2005 Posts: 336 Ride: 1986 v8 blazer Seller Rating: (0)	so what rear end do i need for an 86? ok, so i got an 86 s-10 and im looking for a posi rear with disk brakes, or at least disk brakes... ordred one from a 95 and it was wrong...but it wasnt even disk brakes, im pretty sure it was the 8.5" but waht rear end will fit the 86 and be the same length Thanks

11-14-2006, 11:05 PM	#10
daryla1933 Registered User Join Date: Nov 2006 Posts: 2 Ride: Seller Rating: (0)	s10 rear width? This was great info on the differences between the 7.5 and 8.5 rear. A detail that I need for my project: I've heard that there are different widths depending on whether you have an s10 pickup or blazer and whether it's 2 or 4 wheel drive. I'm looking for something that is: 1. 60" from wheel mounting to wheel mounting. 2. 8.5 ring gear. 3. 3.73 posi. 4. disc brakes. I don't think the zr2 option will work as the measurement is too wide, but maybe you guys have other info?

11-16-2006, 09:22 PM	#12
daryla1933 Registered User Join Date: Nov 2006 Posts: 2 Ride: Seller Rating: (0)	Thanks for your input!

06-16-2009, 01:06 PM	#13
billp Blazin Low Supporter Senior Member Join Date: Nov 2001 Location: near philly Posts: 1,297 Ride: Seller Rating: (3)	S10 8.5 Zr2 Rears Are , I Believe, 65" Long. __________________ 84 xCab S-15. No longer ugly but still quick

07-13-2010, 06:30 AM	#14
Benalex Registered User Join Date: Jul 2010 Posts: 1 Ride: Seller Rating: (0)	It was really a nice experience to read out from here because all the posts are interesting to read out and conating very useful information for the readers as well. __________________ testking 642-901 and 70-450 preparation especially for 1z0-050 and 1z0-051.

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