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 January 1, 1962, who was first employed by the same participating employer periodically from August 15, 1938, until November 13, 1947, who was again employed by the same participating employer from December 1, 1947, until October 10, 1953, and who was again employed by the same participating employer periodically from July 12, 1954, until June 5, 1961, shall be granted prior service credit for all such employment on the effective date of this act. Said prior service credit shall be applicable to benefits payable thereafter. The prior service benefit shall be computed by using a prior service annual salary of one thousand three hundred thirty-four dollars and sixty-seven cents ($1,334.67).