(4) A vehicle equipped and used for plowing snow on other than public ways may be equipped with an auxiliary rotary flashing light that must be mounted on top of the vehicle in such a manner as to emit an amber beam of light over a 360` angle, or an amber strobe, or combination of strobes, that emits at a minimum a beam of 50 candlepower and provides visible light coverage over a 360` range. The light may be in use on a public way only when the vehicle is entering the public way in the course of plowing private driveways and other off- highway locations.

(5) A rural mail vehicle may be equipped with auxiliary lights.

(a) The lights used to the front must be white or amber, or any shade between white and amber.

(b) The lights used to the rear must be amber or red, or any shade between amber and red.

(c) The lights, whether used to the front or rear, must be mounted at the same level and as widely spaced laterally as possible.

(d) The lights, whether used to the front or rear, must flash simultaneously.