I've never owned or ran either prior to this purchase and this diff still sits on my floor awaiting attention, but the GN is an 8.5" ring vs the smaller 7.5" or 7 5/8" MCSS, the GN axles are 28 spline vs 26, the driveshaft will need to be 7/8" - 1" shorter, Eaton units are rebuildable and Auburn is not. Like I said, I'm brand new to these things myself so I'm not a great source. There are some excellent sources on this very forum though.
This thread has some decent info.
**A good chunk pf the 80s SSs had 7.625 rear ends with 3.73s and 28 spline axles. Posi was optional. Normal Montes might have had the 7.5 with 3.08 and down.
gbodyforum.com
These forums do as well.
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