I have a 06 sprinter and am getting a rear end whine when accelarating. It is much more prononced around 60mph. When I take my foot off the gas pedal and coast, it turns into a growling. If I shift to nutreal, it goes away. I'm thinking either a wheel bearing or the pinion gear in the rear differential. There is no change of pitch when turning. I did a search and cant pin point what the problem is. Thanks for any help provided. By the way , the drive shaft was changed to a after market one about 5 months ago. I had also changed the rear end differential fluid at that time. When I checked it , it is still clean with no metal at all. Thanks Fred.