The provisions of this act shall apply to all residency requirements adopted on and after the effective date of this act. Nothing herein shall be construed as to alter, abrogate, repeal or otherwise affect any residency requirement in effect in any local unit by ordinance or resolution, or rule or regulation of a local unit, on the effective date of this act; provided, however, that any amendment, modification or other change in any such residency requirement shall be subject to all the relevant provisions of this act.
N.J.S. § 40A:9-1.9