Every member of said fire department and police department including its officers, but not including the governing authorities of said city on account of their relation as such to said fire department and/or police department, who are members of the disability and relief fund for firemen and policemen shall come under the provisions and benefits of this article and shall receive all benefits provided for in this article. All firemen and policemen who are employed in the said fire department or police department after adoption of a resolution by the municipality in accordance with the provisions of subsection (c) of Section 21-29-17 shall not become members of the disability and relief fund for firemen and policemen.

However, in any municipality having a population of not less than twenty-eight thousand (28,000) and not more than thirty thousand (30,000) according to the 1960 decennial census and located in a county having an assessed valuation in 1969 of not less than Eighty-five Million Dollars ($85,000,000.00) and not more than Ninety Million Dollars ($90,000,000.00), any former member of the fire or police department with thirteen (13) or more consecutive and paid years longevity retirement benefits in the retirement system, who remains in public service of such municipality in an elected capacity which includes ex officio chief of police or fire department, such elected public service shall be credited under this article, when the member pays into the system all employer and employee contributions with any interest or earnings thereon based upon the salary he received during the last six (6) months of his employment as a fireman or policeman prior to his becoming an elected official, and his retirement benefits shall be computed upon the salary so received.