A member whose membership continues under Section 20731 shall be retired for disability and receive a retirement allowance based on the service credited to him or her at the time of retirement during any period in which he or she receives a disability retirement allowance under a county retirement system , subject to the following conditions:
(a)
That the allowance shall not be paid if entry into employment resulting in membership of the county system occurred prior to October 1, 1957, or after
more than 90 days of discontinuance of state service.
(b)
That the allowance shall not exceed an amount that, when added to the allowance paid under the other system, equals the allowance that would be paid if the member’s state service were credited under the other system where retirement is for disability not arising out of or in the course of employment subject to the other system. However, the allowance shall in any event be no less than an annuity that is the actuarial equivalent of member’s contributions.
(c)
That the allowance shall be an annuity that is the actuarial equivalent of accumulated contributions where retirement under the other system is for disability arising out of and in the course of employment subject to the other system.