Headlamps arranged to provide a single distribution of light not supplemented by auxiliary driving lamps shall be permitted on motor vehicles manufactured and sold prior to January 1, 1938, in lieu of multiple-beam road-lighting equipment herein specified if the single distribution of light complies with the following requirements and limitations:
(a) The headlamps shall be so aimed that when the vehicle is fully loaded none of the high-intensity portion of the lamp beam rises above a horizontal plane passing through the headlamp centers parallel to the level surface upon which the vehicle stands, and in no case higher than 42 inches above the level on which the vehicle stands at a distance of 75 and more feet ahead.
(b) The intensity shall be sufficient to reveal persons and vehicles at a distance of at least 200 feet.