quiet whine coming from the rear?

Anyone have a strange whine in the rear? mine has done this since new if i remember correctly. It only does it under acceleration, it is a steady sound never seems to change rhythym, im guessing the belt, almost sounds like a brake lightly dragging…only when you are moving similar to what the old sportsmans used to do all the time at speed. This could be normal which is why my asking. its hard to pin point the location of the sound from the drivers seat.