; (B) any semi-trailer with a gross vehicle weight rating of 10,000 pounds or more that is manufactured on or after the effective date of the rule; and (C) any single unit truck— (i) the bottom of the carriage of which is greater than 22 inches above the ground; (ii) with a gross vehicle weight rating of 10,000 pounds or more; and (iii) that is manufactured on or after the effective date of the rule. (2) Retro-fit requirements Not later than 2 years after the date of enactment of this section, the Secretary shall issue a final rule requiring the installation of side underride guards that meet the performance standards described in paragraph (3) on— (A) any trailer with a gross vehicle weight rating of 10,000 pounds or more that is manufactured before the effective date of the rule required by paragraph (1); (B) any semi-trailer with a gross vehicle weight rating of 10,000 pounds or more that is manufactured before the effective date of the rule required by paragraph (1); and (C) any single unit truck— (i) the bottom of the carriage of which is greater than 22 inches above the ground; (ii) with a gross vehicle weight rating of 10,000 pounds or more