TL;DR I want to know if there's a difference in widths on the 8.5 10 bolt rear end.

I'm looking to do mild. 2" lift, 31's and a rear lock-rite. I've gone the hardcore route in the past, but now I have kids and I just want to build the Blazer for some occasional Saturday fun. I have a non ZR2 2000 two door 4x4 with the 7.5 and GT4 RPO option 3.73s.

First, has anyone had a problem with the 7.5 on 31s? I'm pretty easy on the pedal and I don't let the revs get up or hop the axles. I'd like a selectable rear, but the only thing I've found for the 7.5 is the lock-rite. How close to "explosion" would I be getting with this setup?

Secondly, if a 8.5 is really the better way to go, I'd be inclined to get one because I could also put in a selectable locker like an Auburn Ected. My concern with the swap is the width difference.

I've measured my 7.5 at 59" (WMS/WMS). I've read the 8.5 is just under 63" However I've also heard that the pickup truck ZR2 as well as the 5 speed manual rear 8.5 is narrower than the standard one. I've also heard that the two wheel drive xtreme had a narrow 8.5 in the back. I've searched on BF and online for this information, but found nothing conclusive.

Can anyone offer some clear information on this? You'd think this would be easy to find, but I've found shaky and varied information.

Thanks, Sam

 

You've got a ~58" WMS-to-WMS axle since yours is a 4x4 (2wd are ~54"). Don't get the ected with built in limited slip it is garbage get an E-Locker, secondly I would look at doing a ford 8.8 swap as you will have a lot more gear/differential options, it is stronger and practically a direct bolt in. Donor vehicle would be a 1995-2000ish ford explorer. some come with open diffs and some come with a traction system, there is a tag on the Diff that says the ratio and the diff type. I am only suggesting this because I just went through this and ended up going with the ford. Hope it helps!

EDIT: Ford 8.8 from year explorer mentioned is ~59" WMS-to-WMS, so its about and inch wider then stock; however the front ifs is ~1.5" wider at stock so your basically evening the stance as well!