The mayor of any Class 1 municipality or of any municipality having a population of 250,000 or more according to the last or any subsequent federal decennial census of this state is hereby authorized to employ for and on behalf of said municipality an employee to be known as chief administrative assistant to the mayor whose salary shall be fixed and determined by the mayor, but shall not exceed $39,500.00 annually. The chief administrative assistant to the mayor employed hereunder must reside within the municipality during the term of his employment. He must have had at least five years experience in public or private business in an executive or managerial capacity; provided, however, a majority of the council shall have the authority to approve the appointment of a person having different qualifications upon the recommendation of the mayor. Said chief administrative assistant to the mayor shall not be subject to the provisions of any merit system, but should he be a member of such merit system at the time of his appointment, upon termination of such appointment, he shall have the right to return to the same or higher classification under such merit system with full credit for time spent as such chief administrative assistant as if he had continued in his merit system classification. Appointees under this section may become members of any pension system applicable to general city employees provided application for such membership be made to the board or other authority administering such pension system within 30 days of appointment. This section shall not limit the authority of said mayor to appoint other employees of said municipality under the applicable merit or civil service system, or otherwise, where authorized by any other law.