High Quality Content by WIKIPEDIA articles! The International Trucks 4000 Series, also known as the International DuraStar line, is a medium duty truck. It is available in three variants, which are built on the same chassis. They differ in engines, drivetrains, brakes, and cargo capacity. It is a popular commercial platform used in a wide variety of applications, such as emergency services, towing, flatbed truck and as a cargo box truck. Variants of the Durastar are commonly used as a platform for both school buses and commercial buses.