Any vehicle 80 inches or more in overall width, if not otherwise required by this chapter, may be equipped with not more than 5 identification lamps showing to the front which shall emit an amber or white light without glare and with not more than 3 identification lamps showing to the rear which shall emit a red light without glare. Such lamps shall be grouped in a horizontal row, with lamp centers spaced not less than 6 nor more than 12 inches apart, and mounted on the permanent structure of the vehicle as close as practicable to the vertical center line. Any vehicle may be equipped with one or more side marker lamps, and any such lamp may be flashed in conjunction with turn or vehicular warning signals. Lamps allowed by this section shall be of a type approved by the director.