Canuck

I have the infamous vibration/rough ride at 55-60 mph and my rear seems to be slightly loud. The sound seems to have a revolution? to it as though it happens with something turning in the rear. I have an 02 SS manual with the Auburn rear. The car still drives hard but I would like to solve this problem. Any suggestions are greatly appreciated as I am fearful of spending a fortune on a bunch of replacements when it could be a specific item.