rear end noise

I own a 2000 Mustang Gt. The car has 3.73 gears in it that were either installed by a shop or the previous owner. I have always heard what sounds like gear whine or a bad wheel bearing. Only owned the car for 4 months. Fast forward till today while my dad and I were doing some car work I noticed...

Ive had humming from the rear of my car just about every since ive owned my cobra.... i thought it was my tires... jus put new tires on this week.. and still hums... more like a whomp whomp whomp noise... sounds like bad tires but isnt....ne ideas??