CAL. HSC. CODE § 114321 : California Code - Section 114321

Mobile food facilities that are occupied during normal business operations shall have a clear, unobstructed height over the aisleway portion of the unit of at least 74 inches from floor to ceiling, and a minimum of 30 inches of unobstructed horizontal aisle space. This section shall not apply to vehicles under permit prior to January 1, 1996.