(

a) Notwithstanding any other provision of this chapter, in a county of the fourth class, as defined in Sections and 28025, as amended by

Chapter of the Statutes of 1971, the board of supervisors may, by resolution adopted by majority vote, as part of any negotiated memorandum of understanding with a bargaining unit that represents safety employees, require a safety employee of that bargaining unit or unrepresented safety employee hired after approval of the resolution, to elect in writing, either the pension calculation stated in

Section or the pension calculation stated in

Section 31664.2. The election shall be made within calendar days of beginning employment with the county. If a new safety employee does not elect the pension calculation stated in

Section 31664.2 within days of beginning employment, the new safety employee shall be deemed to have elected the pension calculation stated in

Section 31664. Once made, a safety employee under this

section shall not be permitted to rescind his or her election. (

b) The resolution described in subdivision (

a) may provide a different formula or calculation of retirement benefits for new members of other safety bargaining units or other unrepresented safety employees hired after approval of the resolution, by making any

section of this

chapter applicable to those different safety bargaining units or unrepresented employees, within the safety member classification, pursuant to a negotiated memorandum of understanding as described in

Section 3505.1. (

c) The resolution described in subdivision (

a) may provide a different formula or calculation of safety retirement benefits for new safety members in one bargaining unit than that which is provided for new safety members of other bargaining units or new unrepresented safety members. (

d) A resolution adopted pursuant to this

section or previously adopted resolutions of the board may require members to pay all or part of the contributions by a member or employer, or both, that would have been required if the

section or sections specified within this

chapter were or have been adopted by resolution. The payment by a member shall become part of the accumulated contributions of the member. For those members who are represented by a bargaining unit, the payment requirement shall be approved in a memorandum of understanding executed by the board of supervisors and the employee representatives. (

e) The board of supervisors, in a resolution described in subdivision (a), shall not require that a bargaining unit be divided solely for the purpose of providing different retirement benefits. However, if the members of a bargaining unit within the same or similar membership classification so elect, retirement benefits may be separately negotiated with that bargaining unit. (

f) Notwithstanding any other provision of law, the effective date of a resolution described in subdivision (

a) may be different than the date of the resolution.