74-49a99. Prior service credit for certain employees; basis for computation. Notwithstanding the provisions of K.S.A. 74-4913 to the contrary, any employee of a participating employer with an entry date of January 1, 1962, who became a member on March 15, 1963, and who was employed by such employer from October 15, 1951, until September 20, 1961, shall upon retirement be entitled to receive prior service credit for said participating employment from October 15, 1951, until September 20, 1961. The prior service benefit shall be computed by using a prior service annual salary of four thousand eight hundred forty dollars ($4,840).