Section 39-21-29 - Selling or using lamps or equipment1. No person may have for sale, sell, or offer for sale for use upon or as a part of the equipment of a motor vehicle, trailer, pole trailer, or semitrailer, or use upon these vehicles any headlamp, auxiliary, or fog lamp, rear lamp, signal lamp, or required reflector, or parts of any of the foregoing which tend to change the original design or performance, unless of a type which has been approved by the department. The provisions of this subsection do not apply to equipment in actual use or replacement parts when this section is adopted.2. No person may have for sale, sell, or offer for sale for use upon or as a part of the equipment of a motor vehicle, trailer, pole trailer, or semitrailer any lamp or device mentioned in this section which has been approved by the department unless the lamp or device bears the trademark or name under which it is approved so as to be legible when installed.3. No person may use upon any motor vehicle, trailer, pole trailer, or semitrailer any lamps mentioned in this section unless the lamps are mounted, adjusted, and aimed in accordance with instructions of the department.