175.331  Rights of firefighters under former law.--The rights of firefighters established by any former provisions of this act shall not be impaired nor shall their benefits be reduced by virtue of any provisions of this act; provided, however, that no member may receive the benefits under the former act and also be entitled to receive the benefits under this act. Unless an election is made in writing before January 1, 1964, to the board of trustees, to remain under the provisions of the former act, it shall be conclusively presumed that the provisions of this act as amended, will apply to all firefighters. Members who have retired under the former act prior to the enactment of this act, shall continue to receive their benefits under the former act.