E140 Rear Axle ‘Howling’ Noise

[SmokemanGRP]

I have an E140 (2019 model) with 135 hours. The gears in the rear axle make a ‘howling’ noise. It is most noticeable when the bypass valve lever is pulled out (neutral) and I push in in reverse. It has never leaked any oil. My LA145 (2010 model) with 470 hours doesn’t make this noise nor does my friends D130. Any ideas before I take it to a dealer?

 

[beenthere]

For that, I wouldn't be taking it to the dealer. But do if you want.