Hard up shifting and downshifting. When rapid deceleration at highway speeds transmission harshly downshifted and caused rear tires to skid during icy conditions. Hard/erratic down shifting conditions during icy conditions caused rear end to break loose during uphill climbs. Truck would downshift with loud clunk and drop from 9th gear into 4th or 5th gear and jump RPMs to 3k or more and then shift back to normal over drive gears. Truck is current on ford 23-2250 TSB