Thank you both Chip and Jon for that info... I am still researching the different diff's available and the Mfactory seems to have very good reviews (at least from other car models, haven't seen many Datsuns with them except for a few on here).
I did have another question regarding the 10mm vs 12mm bolts (I honestly do not know what i have yet, but I do think it's a 3.54 gear ratio). You had mentioned in an older post about shims, is that info needed or has this diff been modified to accommodate either bolt size?
At least now I understand that this is a torsen style diff, so much less maintenance (less gear oil changes and no clutches to wear out). The one downfall I've read is some aggressive courses with curbs that get one tire in the air will force it to lose traction, but I don't think i'll be in that scenario often. I'm 95% street, and occasional autocross in a flat parking lot (for now).