Every truck, truck tractor, and bus operated on highways in this State, except as provided in subsection (b) of this section, shall be identified with the name or trade name of its owner, operator, or lessee and shall display: A United States Department of Transportation number; or The number issued by a State agency. This section does not apply to the following if operated intrastate only: Vehicles registered as: Farm trucks under § 13-921 of this article; Farm truck tractors under § 13-924 of this article; or Farm area motor vehicles under § 13-935 of this article; Trucks registered at 10,000 pounds capacity or less; Emergency vehicles; Vehicles used primarily to transport money or commercial paper; Vehicles owned or operated by the State or any political subdivision of the State; or Vehicles operating within 15 days from the date of purchase. The display of identification required by this section shall comply with the regulations promulgated by the federal Motor Carrier Safety Administration relating to vehicles operating interstate, as codified in 49 C.F.R., Part 390.21. This section does not prohibit the display of any additional identification required by other laws of this State or any other state, or by any agency or department of the federal government.