yesterday i was looking at my car just inspecting it and i noticed that there was a little bit of grime on one of the front u-joints. would this b a leaking diff? ive also noticed that the diffs seem to b looser than they used to be. is that leaking or do they all do that over time? if it is a bad diff seal what do i have 2 do to fix it? can you buy a whole new diff because im fairly new and i dont think i could repair it that good.