225 ILCS 610/9.2
Each vehicle issued a Class 1 permit shall have the inscription "Illinois Dead Animal Disposal Permit No....", as assigned; each truck granted a Class 2 permit shall have the inscription "Illinois Scrap and Grease Permit No....", as assigned; and each truck granted a Class 3 permit shall have the inscription "Illinois Hide Permit No....", as assigned. All of these inscriptions shall be painted in a conspicuous place in contrasting color on the left side of the bed of the vehicle in letters not less than 3 inches high. If the vehicle transporting the rendering material or used cooking grease and cooking oil or conveying dead animals to a landfill is not a van type truck, the vehicle bed, as well as any properly identified tanks or barrels used for the transportation of rendering material, or used cooking grease and cooking oil when loaded or partially loaded, shall be covered when traveling highways of the State of Illinois. Vehicle beds shall be leak-proof or constructed so that no drippings or seepage can escape.
Collection vehicles containing rendering material or used cooking grease and cooking oil or used for transporting dead animals, poultry, fish, or parts of bodies thereof shall be thoroughly scrubbed and disinfected after hauling each load, or before proceeding for another load. All vehicle beds shall be painted as necessary, and kept in good condition and repair at all times.
225 ILCS 610/9.2