The provisions of Sections 63-7-31 through 63-7-35, relative to lighting equipment, shall take effect and be operative with respect to equipment installed in motor vehicles after April 10, 1948 and with respect to the equipment on other motor vehicles, the provisions of Laws, 1938, ch. 200, shall govern unless new equipment is installed therein, in which event such new equipment shall be governed by the provisions of said sections.