Notwithstanding anything in subsection 1 of section 304.075 to the contrary, effective August 28, 1996, any new bus to be used to transport children to or from a federal Head Start program shall bear signs indicating that it is a Head Start school bus. Any bus that was used to transport children to or from a Head Start program prior to August 28, 1996, that continues to transport children to or from a Head Start program after such date may bear signs indicating that it is a Head Start school bus.