Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 to the contrary, an employee who became a member of the Kansas public employees retirement system on June 1, 1965, and who was first employed by the Jewell county agricultural extension council, a nonparticipating employer, from June 1, 1953, to May 31, 1964, shall upon retirement be entitled to receive prior service credit for such employment if the Jewell county agricultural extension council has become a participating employer under the Kansas public employees retirement system at the time of the member’s retirement. The prior service benefit shall be computed by using a prior service annual salary of $7,900.