This weekend - we got about 5"-6" of snow on Long Island. After they salted and plowed the roads the Expressway was OK to drive highway speeds on. Well, I was in 4WD high and shifted from 4th to 5th and I heard a strange - grinding like noise coming from the front - the same thing happened on the 4th to 5th downshift. What is it - or what could it be? It only happens in 4WD and at higher speeds.