Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 to the contrary, an 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 July 1, 1971, was first employed by another participating employer on January 13, 1947, to January 8, 1951, and by another participating employer on January 13, 1953, until January 10, 1961, shall upon retirement be granted prior service credit for employment with all participating employers prior to entry date whether such employment was continuous or not. A prior service benefit shall be computed by using a prior service annual salary of one hundred fifty dollars ($150).