I recently just bought a 2003 325i about a month ago from a private seller with about 52,000 miles on it...About two weeks back, I started to hear some whining noise when I was accerelating...I took it to tuffy auto center to get it checked today and they said "My left carrier bearing & pinion bearing in differential assembly are the source and that my differential needs to be rebuilt or replaced." They said they wouldn't be able to do this and that I have to take it to a dealer...Has anybody ever had this problem before??? And would I HAVE to replace the differential or should I be good with just replacing the left carrier bearing & pinion bearing??