At about 30MPH a whirring sound starts from the back end. Volume and pitch increases with speed... independant of road conditions. The noise only accurs when the drivetrain is under load/acceleration. While under load (as on a long grade), down shifting does not affect volume or pitch.
No clunkiness. Tire tread wear is "normal". SLS is working properly.
Any thoughts? Pinion bearing...Drive Shaft support bearing? I do not have a ton of experience in this area.
Thanks in advance!