(a) Unless otherwise provided by local law, vacancies in the governing bodies of all Class 5 municipalities which have existed for more than 60 days shall be filled as herein provided:
(1) If the vacated term has less than six months remaining, then the remaining members of the city governing body shall appoint a successor by a majority vote of those members voting. In case of a tie vote, the mayor, if there is one, shall cast the tie-breaking vote. The successor shall serve the remainder of the unexpired term until a successor has been qualified and elected.
(2) If the term has been declared vacant and has six months or more remaining, the mayor, if there is one, otherwise the senior member of the city governing body, shall call for a special election to fill the vacancy. The successor shall serve the remainder of the unexpired term until a successor has been qualified and elected.
(b) Special elections called pursuant to this section shall be conducted as provided by the general laws of this state regarding municipal elections.
(c) The procedures provided in this section shall be used, unless otherwise provided by local law, for any vacancies existing on or after May 7, 1981.