3.42 with posi question

[bigg502]

I just got a nice 3.42 and posi unit the other day it's a 7.5/8 though I don't guess it'll work in my stock bu rear will it?
what would I need to do to make it work I also have a 84 s10 would it work in that?

 

[monzaz]

As long as the posi unit has 26 spline side gears (both holes in either side of the unit where the bearings are pressed on. ) Yes it will work...

There are 2 series posi units 2.14 -3.08
& a 3 series posi unit that fits 3.23 -4.56 gears.

The posi unit ring gear flange measurement will determine the series of the posi and or open unit. (reference pictures)

If your posi unit is 28 spline you still can use it in the s-10 or the BU BUT you will need 28 spline axle shaft in each of the housings respectfully.

 

[HP JUNKEY]

Like monzaz said, But be aware of 1 thing, The 78-87 G-bodies had both 7.5" {7&1/2}rearends and 7&5/8" rearends with 26 spline axles. The 7&5/8" rears were common in the Monte SS's The only difference is the inner pinion bearing {closest to the teeth} and its race. The 7.5 has a visibly slightly smaller diameter. All other bearings are the same. On the outside the housing looks exactly the same. All the other parts, axles, carriers, backing plates, etc are interchangeable. The Carriers will exchange with all S10's, F-Bodies, and G-Bodies with the correct spline count. I guess GM's thoughts were putting that Whopper of a 305 in the SS's :lol: :lol: would put a strain on the pinion bearing!
Just something to keep in the back of your mind if you are going to replace the Ring and Pinion and/or bearings.
Good Luck!

 

[bigg502]

Thanks guys I guess I need to find someone around here to put them in. I believe I'll put them in the bu. And I'll go with a ford 8.8 in the s10 because it's a easier swap maybe I can get lucky and find a 8.8 with a posi and 373 or 411 already in it

 

[monzaz]

INNER pinion bearing info - ALL 7.5 1982 -1988 were 89249 bearing with 89210 race. This was done across the board on all G-body and s-10 rear diffs. so 1978-1981 g-body rear will still have the older 89449 bearing and 89410 race that came in all the older 8.2 10 bolt BOP and Chevy rears AND 12 bolt truck for that matter.... If you can believe that

7 5/8 was nothing more than the spider gear redesign in the Monte Carlos Yes for the v8-305. That is it...lol. truly.

7.5 spider gears are tiny so that was the thinking on the redesign all the torque gets transferred through the spider gears so they need improving...NOT sure this was a good answer to the problem at hand I LIKE the 8.5 answer WAY BETTER!!!

Good luck on the choices...