What Rear diff choices are there for the IRS from Factory Five

[CraigS]

Did you verify that the 331 ring gear will fit the Torsen center section? I helped a friend swap gears in his IRS and wasn't real happy w/ the carrier bearing shims. I am used to the old 8.8 which had a super selection of shims. The shim kit he got had a minimal selection w/ a lot of thick shims and not a lot of variation.

[qwezxc12]

Did you verify that the 331 ring gear will fit the Torsen center section? I helped a friend swap gears in his IRS and wasn't real happy w/ the carrier bearing shims. I am used to the old 8.8 which had a super selection of shims. The shim kit he got had a minimal selection w/ a lot of thick shims and not a lot of variation.

Craig,

I'm at that stage right now; I just dropped off the gear set last night to the shop doing the work. As edwardb said, I did not consider this to be a DYI job.
The 3.73, 3.55, and 3.31 are all supposed to fit the Torsen, it's the 3.15 that doesn't.

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The kit I got included the new gear set, M12 ring bolts, pinion nut and spacer, pinion head and tail bearings, and seal. I have the original shims from the diff when it was disassembled and the shop has some. The diff felt great from Ford; ~.008" backlash IIRC.

[Jim1855]

I have the aluminum case, 3.31, Torsen. The full build was supplied by Mike Forte. Call Mike.

And a cheap promotion. I have an iron case, 3.55 Traction-Loc in the box.

Jim

[KirkS]

I got a 3:31 iron case that came out of a 2015 from midwaymustangparts. They're out there, don't know how rare. I want a cruiser, not a drag racer.

Collecting parts for a future Gen III build, Kirk