Well, the service manager initially said it was a wheel bearing, but then called back and said 'rear diff and drive shaft' were bad. Wheel bearing is usually noticable as a different sound when turning, right? This is definitely drivetrain as it is very noticable when the drive train is loaded (as in accelerating or maintaining speed) and the sound almost totally goes away when decellerating.
Before I took it in I could have sworn it was coming from up front and thought it was transmission or wheel bearing.
I should hear from them re: parts arriving next week.