Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 to the contrary, any employee of a participating employer with an entry date of January 1, 1962, who became a member of the Kansas public employees retirement system on April 1, 1964, and who was employed by another participating employer on December 1, 1945, until September 1, 1959, shall upon retirement be entitled to receive prior service credit for all employment prior to January 1, 1962. The prior service benefit shall be computed by using a prior service annual salary of six thousand nine hundred dollars ($6,900).