If the Authority acquires a transportation system in operation by a public utility, all of the employees in the operating and maintenance divisions of such public utility and all other employees except executive and administrative officers and employees, shall be transferred to and appointed as employees of the Authority, subject to all rights and benefits of this Act, and these employees shall be given seniority credit in accordance with the records and labor agreements of the public utility. Employees who left the employ of such a public utility to enter the military service of the United States shall have the same rights as to the Authority, under the provisions of the Service Member Employment and Reemployment Rights Act as they would have had thereunder as to such public utility. After such acquisition the authority shall be required to extend to such former employees of such public utility only the rights and benefits as to pensions and retirement as are accorded other employees of the Authority.