The RK62 truck entered the first-generation in January 1957, but the model name remained unchanged at the time. Its production plant was moved from Toyota Auto Body to Kanto Auto Works, and the styling was renewed to offer various body types such as panel van, route van, light van, advertising car, and route bus. In April 1958, the RK70 model with a loading capacity of two tons replaced the RK62, as the output of the Type R engine increased from 55 to 58 hp. As the maximum dimensions of small automobiles were expanded soon afterwards, the RK75 was announced in July 1958, with the wheelbase lengthened from 2,530 mm to 2,750 mm and the bed length from 2,500 mm to 2,890 mm.

The RK85 was announced in April 1959, replacing the predecessor's floor shifter with a column shifter and changing the seats to accommodate three people. First among Japanese-made trucks, this model was able to tilt the entire cab forward to facilitate engine maintenance. In June 1959, the model name was changed from Route Truck to Dyna in a naming competition participated by Toyota and sales channel employees. After further improvements in the chassis and brakes to enhance its carrying capacity, the Dyna RK160 was released in January 1962, equipped with a 1.9-liter 3R engine.