Upon request, the department shall issue identical plates that contain the word “SHERIFF” for the vehicles used and owned by a sheriff’s department and the word “POLICE” for the motor vehicles used and owned by a city’s police department. The plates must be in black letters and on the designed background in use at the time of issuance. The plates must be provided at actual cost. Notwithstanding section 39-04-11, the plates are the property of the law enforcement agency to which issued. At an appropriate time, replacement of the plates must occur whenever the designed background used by the state changes. Notwithstanding section     39-04-11, a motor vehicle that displays a plate under this section must have a clearly visible distinctive identification number on the rear of the vehicle assigned by the appropriate law enforcement agency.