(1) In lieu of any other contingent expense allowance now provided by law for the Prosecuting Attorney of the Nineteenth Judicial District, the prosecuting attorney shall hereafter receive a contingent expense allowance to be borne by the respective counties of the Nineteenth Judicial District as follows: Benton County $1,750; and
(2) Carroll County $750.
(3) The counties in the Nineteenth Judicial District shall pay the above prescribed annual amounts in equal monthly installments.