In the appointment of a county superintendent of airports, the joint commission shall proceed as is provided for a county airports commission, and the Department shall certify the eligible candidates to each of such county boards who may appoint the same candidate to be superintendent or if unable to agree on the same person, may elect different eligible candidates. If the same person is elected to so serve by both boards the compensation and necessary expense of such superintendent shall be shared as is hereinafter provided for other joint expenditures. In event the two county boards do not concur in the appointment of the same person, each county shall pay the entire compensation and expense of such superintendent. In event one county fails within ninety days after the certification of the eligible candidates to appoint one such person to the office of superintendent, the person elected by the other county shall serve for both counties and his compensation and expense shall be shared as a joint expense. If both counties fail to appoint one of such eligible candidates to serve as superintendent, within such ninety day period, the joint commission shall appoint one of such eligible candidates as superintendent, fix his salary and his compensation and necessary expense shall be shared by the two counties as aforesaid. In any case, such superintendent or superintendents shall act under the direction of the joint commission without respect to county lines and the consent of the county boards shall not be required.
     In preparing and submitting resolutions to the county boards providing for the levying of taxes, the borrowing of money, and in the appropriation and expenditure of money, the joint commission shall determine the amount of money needed for joint airport purposes and the counties shall levy taxes to raise such amount of money, in their respective counties, at such rate, not to exceed one mill on the dollar of the assessed valuation of the counties as evidenced by the last assessment roll on which county general taxes were extended, in such proportion as the assessed valuation of the property of one county bears to that of the other county.
     The county clerk of the county having the larger population shall act as clerk of the joint county airport commission and have custody of the records thereof. Nothing herein shall prevent an agreement between such county boards providing that the county clerk of the county having the lesser population shall so serve. Unless specifically prescribed in this section, the joint commission and the two county boards shall be governed by the requirements of this Act as it applies to a county airports commission and the county board.