I've been thinking about a rearend swap and I noticed the some S-10 Zr2s come with 30 spline axles and a 8.6 ring gear and some even have posi and disc brakes. My question is how wide is this rearend and did it come in any other GM vechicles? I have a neighborhood pick and pull that charges a flat 150.00 for any rearend so it might be worth my time to keep a lookout for one of these if one comes in.Thanks

i think it was available in all the S series vehicles with certain options.
this would be S10, S15, Blazer, Bravada, Jimmy, etc..

If I remember correctly, an S-10 rear is 3-4 inches narrower than a first gen. rear. I know the spring perches are way off.

Mark

The weak point on those rears is the pinion diameter. It will break much quicker under high torque than an 8.5 out of the mid third gen Novas.

As far as I know the pinion shaft size is the same on all of the 8.5 and 8.6 rear ends.

big gear head, I was browsing the junkyard today and saw a 72 Caddy with the weirdest rear I've seen, it had 12 bolts on the cover but the pinion was cast really low in the case and had bolts on the yoke side. Not thinking of a purchase but is this a common GM rearend?

Yes, this rear end was used in many of the big GM cars, even some Chevy wagons. There are not any good parts available for it, even though many of them were posi.

I found out more on the zr2 s-10 rearend. It's 63" drum to drum and the perches would need to be rewelded, they are too narrow. I think these rears come in GM big cars also, they have 30 spline axles, and the carrier has a little larger bearings in the newer rears. The posi unit looks more like an Auburn instead of the cheesy Gov-Lok. THis would be a great swap if it wasn't so wide. The regular S10 rear is the smaller 7.5.

The 2WD 4.3 5 speed S trucks had the 8.5. This rear end is about 4 inches narrower than a Camaro rear end. The 8.6 rear end has larger differential bearings. They are actually the very same bearings that are used in the 12 bolt.