The noise is definitely more pronounced when in neutral and the rear end is free rolling. The noise can be heard through a stethoscope coming from inside the rear dif. We drained the dif. and the oil was very dark (not burnt) with a slight brass metallic sparkle to it. There was also lots of sludge on the magnet, but no metal fragments. I was hoping to avoid a full tare down, but I think that it's going to be necessary.