Part IV, Chapter V of the new Act (limited to the portion of the domestic source income set forth in Article 161, item (iii) (Consideration for the Rental of Real Property and Similar Property) of the new Act that relates to consideration for the rental of a vessel or aircraft) applies where a contract for the rental of such a vessel or aircraft is concluded on or after the effective date (including, where the contract period of such a rental contract concluded before that date is renewed on or after that date, that renewal).