Looking for some help and guidance with a drivetrain noise I cannot diagnose. I have a 2002 F350 diesel and have noticed over the past couple thousand miles a noise from the drivetrain that is hardtop identify. It is not brake related ( new and unaffected by brake application) and not rpm related. Most noticeable at around 50mph. Not tires and they are new and noise persists. Front end has been apart for new hubs, brakes, rotors, wheel bearings. Noise continues. It has an oscillating quality and is somewhat like a lower pitch whine which gets more prominent as speed increases. Wondering about bearings associated with drive shafts? Are there some things I can check underneath to help diagnose the issue? Really appreciate the help

 

Have you checked your diff to see if they are low on oil?
Maybe worn out lsd if ypu have one

 

I have not, but I would expect some vibration with low diff oil. Wondering about a bad/worn carrier bearing or perhaps a bearing that supports the front axle?? JUst spent about $1000 to sort out my autolock hubs ( turned out to be a brand new PVH solenoid that was put in to replace a bad on. Dealer worked all around it assuming the new part couldn't be bad. Painful. Thanks