Establishments primarily engaged in manufacturing or assembling complete passenger automobiles, trucks, commercial cars and buses, and special purpose motor vehicles which are for highway use. This industry also includes establishments primarily engaged in manufacturing chassis and passenger car bodies. Such establishments may also manufacture motor vehicle parts, but establishments primarily engaged in manufacturing motor vehicle parts except chassis and passenger car bodies are classified in Industry 3714. Establishments primarily engaged in manufacturing truck and bus bodies and in assembling them on purchased chassis are classified in Industry 3713; those manufacturing motor homes on purchased chassis are classified in Industry 3716; those manufacturing motorcycles are classified in Industry 3751; those manufacturing industrial tractors are classified in Industry 3537; those manufacturing other wheel tractors, except contractors off-highway types, are classified in Industry 3523; those manufacturing tracklaying and contractors'off-highway type tractors are classified in Industry 3531; those manufacturing combat tanks and self-propelled weapons are classified in Industry 3795; and those manufacturing stamped body parts for passenger cars are classified in Industry 3465.