Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 to the contrary, an employee of a participating employer who was employed on the employer’s entry date of January 1, 1968, who was first employed by said participating employer on January 14, 1963, and who had previously been employed by another participating employer from March 1, 1956, until November 30, 1960, shall upon retirement be entitled to prior service credit for all service with any participating employer prior to January 1, 1962, whether such service was continuous or not.