2.7 LITER. Engine cover bolt. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure the Radiator Support Air Duct to it's mounting point. Engine Cover Bolt. Horn Mount Bolt. and Washer Assembly. and Washer Assembly - HEX. HEAD. Mount. Engine Cover. High note. Housing. Low note. Radiator Support Air Duct.