California Code, Health and Safety Code - HSC § 18087.5

(a) The applicant for registration under this part of a manufactured home, mobilehome, commercial coach, or truck camper previously registered outside this state shall surrender to the department all unexpired license plates, seals, certificates, or other evidence of foreign registration which are in the applicant's possession or under the applicant's control. The department may require a certification from the jurisdiction of last registry when the applicant fails to surrender the last issued unexpired license plates.

(b) Upon application made at the time of their surrender to the department and upon payment of a fee of three dollars ($3), the department shall return the unexpired license plates to the official in charge of the registration of manufactured homes, mobilehomes, commercial coaches, or truck campers in the state of issue of the license plates.