The International Harvester S-Series was a family of light and medium trucks that debuted for the 1956 model year. The S-Series succeeded the International Harvester R-Series, and was offered in a range of payload capacities. These trucks were powered by a variety of inline six engines, with the size and power depending on the Gross Vehicle Weight. The International Harvester S-Series was in production until 1957, when it was replaced by the International Harvester A-Series. The S-Series name would be used again to designate a range of medium and heavy duty trucks known as the International Harvester S-Series Medium & Heavy Duty.