Be it further enacted, That the council shall appoint an officer of the city who shall have the title of city manager and shall have the powers and perform the duties in this charter provided. No councilman or former councilman shall receive such appointment unless he shall have vacated the office of councilman by resignation or otherwise at least one (1) year prior to receiving such appointment. [As amended by Priv. Acts 1967, ch. 485, § 2]