31 Spline 5 lug Axels/ Eaton Posi

You should be ok. I am using an Aurbun posi and 31 spline axels with 4 lugs. My car drives just fine on the street.

Eaton is a very reputable differential maker. I have heard good things about them and their reliabilty. The auburn I have heard mixed reviews about longevity though.

As for the 31 spline axles, it all depends on your setup. Seeing as you have a s/c in the list I take it that you are serious with the power. If you are pushing 400+ hp at the rear wheels OR close to it and drive it aggressivley, then the torque monster the 5.0 is will have it's say if you stuck with the 28 spline long-term.

yeah good move, i also just recently got some 31 spline Moser axles and an Eaton diff and i absolutly love the Eaton.