Any city with a population of 1,000,000 or more, and any agency thereof, which has established any pension and retirement plan which requires officers and employees of one sex to pay greater contributions than those of another sex who are the same age shall revise the plan so that the contributions are the same commencing with contributions for service on and after January 1, 1975. This section shall not be construed as requiring or authorizing an increase in the contributions of any members of a pension and retirement plan.

This section shall not be applicable to the Public Employees’ Retirement System.