Section 506 - Payment of tax1. At the time of filing a return, as required by this article, each carrier shall pay to the tax commission the tax imposed by this article for the period covered by such return. Such tax shall be due and payable at the time of filing the return or, if a return is not filed when due, on the last day on which the return is required to be filed. The tax commission may grant a reasonable extension of time for paying the tax whenever good cause exists.2. The fees, taxes, penalties and interest accruing under this article shall constitute a lien upon all motor vehicles and vehicular units which are owned by such carrier or of which he has the lawful use or control. The lien shall attach at the time of operation of any such motor vehicle or vehicular unit within this state and shall remain effective until the fees, taxes, penalties and interest are paid, or the motor vehicle or vehicular unit is sold for the payment thereof. Such liens shall be paramount to all prior liens or encumbrances of any character and to the rights of any holder of the legal title in or to any such motor vehicle or vehicular unit, provided, however, that:a. No lien for any additional tax assessed pursuant to this article shall be enforceable against any motor vehicle or vehicular unit which prior to such assessment had been transferred in good faith to a bona fide transferee for value.b. The lien of such tax shall be subject to the lien of any indebtedness secured by a chattel mortgage or conditional sales agreement existing against such motor vehicle or vehicular unit previous to the time when such tax became a lien, if:(1) Such indebtedness was incurred in good faith to secure a portion of the purchase price of such motor vehicle or vehicular unit, and(2) Such indebtedness is secured by a chattel mortgage or conditional sales agreement duly filed as required by law, and(3) Such chattel mortgage or conditional sales agreement was not given, directly or indirectly, to any officer or stockholder of the corporation owning or having the lawful use or control of such motor vehicle or vehicular unit, whether as a purchase money mortgage or otherwise. The lien of such tax shall be enforceable, however, as to any equity after the encumbrance of such chattel mortgage or conditional sales agreement. In the event a motor vehicle or vehicular unit subject to such tax lien is repossessed by a chattel mortgagee or a conditional vendor such motor vehicle or vehicular unit shall not be sold at public or private sale unless at least five days notice of the time and place of such sale is served by registered mail upon the tax commission in Albany.