N.J. Stat. Ann. § 43:15A-112.1

2. If a referendum is held pursuant to section 6 of P.L.1955, c.38 (C.43:22-12) and if a majority of the members of a county pension fund established pursuant to R.S.43:10-1 et seq. for employees of a county of the first class having a population of less than 800,000 according to the 1980 federal decennial census qualified to vote in the referendum vote to be covered under the terms of the federal Social Security Act, the pension fund shall not be terminated and members shall remain in the pension fund. The pension fund shall be divided into two divisions, one to be composed of positions of members who desire Social Security coverage and the other to be composed of positions of members who do not desire that coverage.