Guys,
There is a "whirring" noise coming from the rear end of my car as I drive. It has progressively gotten worse over the past couple of months. The noise starts at around 25mph and gets louder as i reach 75mph. It is a consistent sound when I have my foot on the accelerator. It seems like the sound is lessened as I coast at speed anddon't have my foot on the accelerator.
I think it may be the differential or a wheel bearing. I had the differential oil changed 100 miles ago and the sound stayed the same. I switched from my summer rims/tires to my winter/rims tires in December and the sound stayed the same.
Anybody else have this problem? Where can I get my diff rebuilt if that's the cause?

Thanks for any help.

__________________
Ed
-1984 Mercedes 190D 2.2 5-speed gray market(bought@30,000 miles) (Sold back to original owner@170,000 miles)
-1999 Mercedes E300DT (245,000 miles)
-1999 Mercedes S500 Grand Edition (80,000 miles)