Tengis First off you need to pull the diff and inspect it for damage and go from there.. As for the magnent thats normal wear for a hard driven car.. Or some of it could be cause by the pin floatinf around inside there?? Its not shifting funny is it? Because I don't see the roll pin from the diff getting far in the trans with out causing major damage.. If its shifting good no hard shifts or anything weird i'd be kind to it and drive it. And you have a pm about the info you asked me in your other post