Okla. Stat. tit. 70, § 70-9-103: Purchase or contract for use of vehicles - Lettering

The board of education of any school district authorized to

furnish transportation to school children may purchase and maintain

suitable vehicles for such use and/or may contract with responsible

individuals or another school district to furnish all or part of

said transportation. All such contractors, however, shall be

subject to statutory provisions relating to the transportation of

school children. Every vehicle with a capacity of ten passengers or

more used in transporting school children shall have painted in

letters not less than eight (8) inches in height on the front

thereof the words, "SCHOOL BUS," and on the rear thereof in letters

of the same size, "SCHOOL BUS."