Coasting whine around 60mph
 

Hi,
My 117,000 mile 3.0D has started to develop a bit of a whine when you take your foot off the accelerator, most noticable at around 60mph. I used to have a high milage E39 which did the same thing and I assumed it was the diff, never did anything about it. Its difficult to locate but I assume its the drivetrain. Any thoughts on whether it would it be some play in the rear diff, gearbox or a wheel bearing starting to go?
thanks
Rob

2004 E53 3.0D sport