No election filed by any public entity, as defined by

Section 605, under any provision of this division shall be effective for service performed after December 31, 1977, and included in “employment” pursuant to

Section 605, except that elections approved under subdivision (

b) of former

Section as in effect prior to January 1, 1978, shall continue in effect as of such date with respect to disability insurance coverage for those employee classifications that are exempt from civil service or merit system status who perform work equivalent to those employees of the building trades crafts that are covered by collective-bargaining agreements with respect to wages, hours, fringe benefits, and other terms and conditions of employment. No election filed by any nonprofit organization under any provision of this division shall be effective for service performed after December 31, 1977, and included in “employment” pursuant to

Section 608. All such elections for coverage filed prior to January 1, 1978, shall be terminated effective December 31, 1977, except as otherwise provided by this

section and except that elections to reimburse benefits shall continue in effect, subject to

Section 803, unless terminated by the public entity or nonprofit organization, and it shall remain liable for its proportionate share of the additional cost of benefits paid, or of the cost of benefits (including extended duration benefits and federal-state extended benefits) paid and charged to its account in the manner provided by

Section which are based on wages paid for services during the period of any election for reimbursement of benefits.