DRIVER WAS ON THE STOCKPILE, TRUCK FACING DOWN HILL. TRUCK BED WAS FULLY RAISED. DRIVER PULLED FORWARD AND STOPPED. BED STARTED ROCKING FROM SIDE TO SIDE, THEN FELL OVER. CAB STAYED UPRIGHT. B ED WAS ON THE (DRIVERS SIDE) GROUND, ON ITS SIDE. STOCK PILE WAS LEANING TO THE DRIVERS SIDE.