The Commissioners of the Postal Rate Commission shall serve for terms of 6 years except that—
(1)the terms of the Commissioners first taking office shall expire as designated by the President at the time of appointment, 1 at the end of 2 years, 2 at the end of 4 years, and 2 at the end of 6 years, following the appointment of the first of them; and
(2)any Commissioner appointed to fill a vacancy occurring before the expiration of the term for which his predecessor was appointed shall serve for the remainder of such term.