well, I was on the freeway last night, and I noticed a lot of noise comming from my rear... I do race my car, and am kinda hard on her... the noise is kinda a "whirring" noise... it isn't time to rebuild it, is it? if so, can I just replace the gears and bearings?

stupid suberbian car owners!) anyway, went on a 400+ miles road trip to Westport this weekend, took the stang, and the whirring noise is still there... can't figure this one out... any ideas guys?