(a) The proceeds of the thirteen cents ($.13) diesel excise tax imposed by this article, when collected, shall be applied as follows:

(1) For payment of the costs of collection thereof, being the amount appropriated for each fiscal year by the Legislature to the department for the administration of this article.

(2) For payment of the principal of and interest on bonds issued after October 1, 1969, and prior to December 1, 1977, by the Alabama Highway Authority, a public corporation and instrumentality of the state, all in the manner and to the extent and subject to the priorities as to rank as are provided in the respective statutes under which the bonds were issued.

(3) For payment of the principal of and interest on bonds and other obligations, including refunding obligations, issued after December 1, 1977, by a public corporation existing at the time of issuance under the laws of Alabama pursuant to then existing statutory or constitutional authorization, or by the State of Alabama pursuant to authorization, effective at the time of issuance, under the Constitution and laws of the state, and for which the excise tax imposed by this article shall have been appropriated and pledged in a then effective statute or constitutional provision, including any enabling act under a constitutional provision, all in the manner and to the extent and subject to the priorities in rank as may be provided in the statute or constitutional provision or in an authorizing resolution thereunder.

(4) The balance shall be covered into the State Treasury to the credit of the Department of Transportation to be used exclusively in the construction, repair, maintenance, and operation of public roads and bridges in this state, including any toll road or toll bridge constructed by the Department of Transportation or maintained and operated by it or under its supervision.

(b) Revenues received or collected from the additional six cents ($.06) excise tax by the department upon the selling, use or consumption, distributing, storing, or withdrawing from storage in this state of diesel fuel remaining after the payment of the expense of administration and enforcement of this section shall be distributed as follows:

(1) Four and sixty-nine one hundredths percent shall be distributed equally among each of the 67 counties of the state monthly. These funds shall be used by counties for the purposes specified in paragraph a. of subdivision (2) of subsection (a) of Section 8-17-91.

(2) Ninety-three one hundredths of one percent shall be allocated among the incorporated municipalities of the state and distributed and used as provided in paragraph c. of subdivision (2) of subsection (a) of Section 8-17-91.

(3) The balance shall be paid to the State Treasury to be used for highway purposes by the Department of Transportation.

Provided, that for the first five full fiscal years commencing October 1, 2004, if distributions to the counties and municipalities provided for in subdivisions (1) and (2) above are insufficient to ensure, in combination with the distributions provided in Section 8-17-91, that the counties and municipalities receive no less than the distributions received for fiscal year 2003 under the previous provisions of Section 8-17-91, then the above percentages shall be adjusted accordingly. After the first five full fiscal years, the above percentages shall not be adjusted.