Gear boxes and parts thereof, for the industrial assembly of: pedestriancontrolled tractors, motor cars and vehicles principally designed for the transport of persons, vehicles for the transport of goods with compressionignition internal combustion piston engine "diesel or semidiesel engine" of a cylinder capacity < 2500 cm³ or with sparkignition internal piston engine of a cylinder capacity < 2800 cm³, special purpose motor vehicles of heading 8705, n.e.s