I looked through many pages on this site for info on diagnosing rear hubs and diffs, and for the life of me I couldn't find it. Recently my truck started making a horrible grinding noise connected to the turning of the rear wheels. I can't tell if it's a bearing or the diff. The lsd seems to be working but for how long? How east is it to fix or replace those parts? And is there a write up I can be referred to?