I've been reading all the above posts to see if the ' noise ' I hear on mine has the same cause --- but it doesn't sound like any of all your descriptions . The noise I hear is under accelleration but not if ' fed ' the throttle ONLY if pushed hard but at all speads and rev's . More a resonating with deep sounding tone . It won't do it just cruising regardless of the speed , be it 60 or 130 mph --- only on hard accelleration.
I was thinking bearings somewhere , in the drive train but not wheel bearing as there's no vibration.