(a) Where there are multiple persons meeting the definition of manufacturer or remanufacturer, each such person must comply with the requirements of this part that apply to manufacturers or remanufacturers. However, if one person complies with a requirement, then all such persons will be deemed to have complied with that specific requirement.

(b) Where more than one entity meets the definition of manufacturer or remanufacturer for a particular locomotive or locomotive engine, and any one of the manufacturers or remanufacturers obtains a certificate of conformity covering such locomotive or locomotive engine, the requirements of subparts C, D, F, and G of this part shall apply to the manufacturer or remanufacturer that obtains the certificate of conformity. Other manufacturers or remanufacturers are required to comply with the requirements of subparts C, D, F, and G of this part only when notified by the Administrator. Such notification by the Administrator shall specify a reasonable time period in which the manufacturer or remanufacturer shall comply with the requirements identified in the notice.