The s-10 rears IMO are underestimated big time as far as strength.


My bro had a stock open rear axle (off an 83), he beat on it with a 520tq BBC, then went to another s-10 rear (off a 90 model I believe) with 3.73 posi, not because the first broke, just because he wanted a posi and more gear and it was cheap, beat on it some more, held up fine as a daily driver for years. Neither were the "stronger" stock axles but held up fine. Don't think you'd have any trouble with a 305.

...But they don't have the 31-spline axles and disc brakes that the Explorer rears have. They have 28-spline axles making them just as strong as the S10 rear end.

I have never figured why so many people go by the backing plate to backing plate. What I really want to know is where the wheels are going to sit. I always go by WMS-WMS (wheel mating surface).

2wd S10 rear end:
54-3/8" WMS-WMS
38-1/2" center pin to center pin.
Pinion offset 1" to drivers side (this was on my 8.5" axle and might be different on a 7.63" axle)

4wd S10 rear end:
From what I understand is 4" wider then 2wd so about 58-3/8" WMS-WMS
Spring spacing same as 2wd and I'm guessing the pinion offset is the same

Ford Explorer 8.8"
59-3/4" WMS-WMS
39-1/4" center pin to center pin (I have heard of people cramming these into S10's without moving the perches)
Pinion offset 2-3/16" to passenger side
There is a short side and long side axle shaft. You can narrow just one side and use 2 short side axle shafts. I don't recall how much this will narrow the axle but I think it will also put the pinion more in the center.

The newer "stronger" S-10 rear axles can be found with disk brakes.


I agree though, the explorer 8.8" would be a good option.

That 8.5 S10 rears are just about Impoassible to find. and if you do, you will pay premium

Do you want one?

I wasn't trying to say that he should (or needs to) get the 8.5". Just that that was what the measurement came from. I guess I could traipse through the weeds in my backyard and get the measurement from the 7.5" axle it replaced...I'm just too lazy and it still might not be the same as the 7.63" axle that was recommended he use.

I payed $550 total for my 8.5" w/ disc brakes and Gov-Bomb and it only took me 2 years to find YMMV

There are still plenty of places to get the 8.5 rears. You just need to look around. And if they are bad you can still buy the gears to put in at a very low price. Plenty of places on the internet to get the gears.

If you can find an s10 extreme in a wrecking yard they all came from factory with posi all others unless special orderd came with open diff. If you can find a s10 blazer they came with disc brakes also.

No GM truck that I know of came from the factory with a Positraction® differential after 1972. '73 was the first year for the "Gov-Lock" which they still use (as well as the new Eaton electric locker on H2's and maybe H3's). The gov-lock isn't my favorite diff (far from it which is why I called the one in mine a Gov-Bomb) but at least in normal driving you will never know it is there and it might keep you from getting stuck in the mud/snow. It is a locking differential and not a limited slip.

The eXtreme's (zq8) also sometimes came with the 3rd "kicker" shock to help traction.

The above is true , but not 8.5 S10 rears, mostly from an Xtreme

The 8.5s were found on some 96 and up 4.3s with the 5 speed manual, and i believe the 8.5s have 30 spline axle shafts. I bought one last year and it was about $400.00 which i didnt think was to bad.