Hi all

My e61 535d has now only covered 108,000 miles however in recent times I have started to hear a tranmission type whining noise coming from the rear of the car.

The noise appears at 90mph. Can be driven through and disappears at 95mph onwards. Is faintly heard below 90mph but only just. It is present when the accelerator is pressed and disappears when it isn't. Also goes if in Neutral so assume it is definately drive related.

Possibles@-

Gearbox
Rear diff
Prop shaft bearing

Any suggestions please ? I might sound like I know what I am doing but I dont. a little knowledge and all that.....
Thanks in advance