(a) Any person who, as of September 5, 1973, is covered or is eligible to be covered under the Employees' Retirement System of Alabama and who, prior to such coverage or eligibility for coverage, served as an elective official of the state government or a department head authorized to exercise sovereign power of the state shall have credited to him one year of creditable service for each year served as such elected official or department head, not to exceed eight years; provided, that such person shall pay into the retirement system the employee's part of the cost or contribution based on the salary paid to such person during the time of his service as an elected official or department head, with such cost or contribution to be calculated at the percent or rate in effect on September 5, 1973.

(b) This section shall apply only to those persons who, at the time of their retirement, have sufficient creditable years of service under the Employees' Retirement System to equal 10 years inclusive of the years earned as an elected official or department head.

(c) The employee's contribution for the years of service as an elected official or department head shall be paid by such employee within 60 days after he shall have completed the necessary years of employment as set out in subsection (b) of this section; except, that should said employee have completed the necessary years of service as set out in subsection (b) of this section, he then shall pay said contribution within 60 days after September 5, 1973.