You're positive it's the trans? I have a '01 Durango with a bad pinion bearing and it makes noise when applying light throttle, but quiets way down when I let off. Sounds pretty familiar...
That's a good thought...but 1)the noise definitely doesn't sound like it's coming from the rear 2) Can't find any load/speed conditions when the noise can be repeated in first gear 3) Going into neutral completely quiets it down (I know this changes load conditions so it doesn't entirely rule out bearing) and 4) the noise was present before and after completely rebuilding the rear end.
