(a) Each replacement part for a part specified in § 541.5(a) must have the registered trademark of the manufacturer of the replacement part, or some other unique identifier if the manufacturer does not have a registered trademark, and the letter ‘‘R’’ affixed or inscribed on such replacement part by means that comply with § 541.5(d), except as provided in paragraph (d) of this section. In the case of replacement parts subject to the marking requirements of this section, which were not originally manufactured for sale in the United States, the importer of the part shall inscribe its registered trademark, or some other unique identifier if the importer does not have a registered trademark, and the letter ‘‘R’’ on the part by means that comply with § 541.5(d)(2), except as provided in paragraph (d) of this section.