California Code of Regulations
Title 13 - Motor Vehicles
Division 2 - Department of the California Highway Patrol
Chapter 6.5 - Motor Carrier Safety
Article 9 - Additional Equipment Requirements for School Buses
Section 1274 - Used or Changed School Bus

If a new or used body is placed on a new or used chassis, or a used vehicle not previously certified by the Department for use as a school bus is placed into service as a school bus, the vehicle shall comply with all current regulations and laws applicable to new school buses, except that Federal Motor Vehicle Safety Standards specifically adopted by reference in this title shall apply only when a vehicle was manufactured on or after the effective date of the standards. A previously certified bus reinstated in school bus service by the same or different owner shall meet the requirements of all regulations and laws that would have applied if the bus had not been removed from school bus service.