California Code, Public Utilities Code - PUC § 7578

(a) The contract is evidenced by an instrument executed by the parties and duly acknowledged by the vendee, lessee, or bailee, as the case may be, or duly proved before some person authorized by law to take acknowledgments of deeds, and in the same manner as deeds are acknowledged or proved.

(b) Each car or locomotive engine so sold, leased, or hired, or contracted to be sold, leased, or hired has the name of the vendor, lessor, or bailor plainly marked in letters not less than one inch in size on each side thereof, followed by the word “owner,” or “lessor,” or “bailor,” as the case may be.