The turnpike revenue bonds, notes or other obligations issued under the provisions of this act shall not be deemed to be a debt of the Commonwealth or a pledge of the faith and credit of the Commonwealth, but such bonds, notes or other obligations shall be payable solely from revenues of the Commission, including tolls, or from such funds as may be available to the Commission for that purpose. All such bonds, notes or other obligations shall contain a statement on their face that the Commonwealth is not obligated to pay the same or the interest thereon except from revenues of the Commission, including tolls, or from such funds as may be available to the Commission for that purpose, and that the faith and credit of the Commonwealth is not pledged to the payment of the principal or interest of such bonds, notes or other obligations. The issuance of turnpike revenue bonds, notes or other obligations under the provisions of this act shall not directly or indirectly or contingently obligate the Commonwealth to levy or to pledge any form of taxation whatever therefor or to make any appropriation for their payment.