When Case began to modernize their lineup, the started in 1953 with their first diesel engine tractor, the Model "500." The "500" produced 56 HP on the drawbar and became a respected engine. Two years later, Case brought out the "400" series tractors with 44 HP, and the "300" with 23 HP. From 1956-58, the offered the Model "350" with 42 HP. Then, in 1957, the Model "600" joined the lineup.