In 1957, G.O. Noville & Associates proposed developing an amphibious tank in line with a concept from George Noville. It was designated ATAC II (Amphibious Tank Alternate Concept, second variant). An interesting albeit expensive project was developed for a vehicle with a 90 mm gun, a jet drive, hollow aluminum rollers, and other innovations. At the same time, the military wanted to produce a cheaper light tank, primarily to ensure that it could be transported by C-130 Hercules aircraft. In order to do this, the tank's amphibious capability was removed by replacing the bogie wheels with steel ones. However, the weight and cost reduction turned out to be so insignificant that the project was discontinued before a prototype was built. The M551 Sheridan tank became a priority area for development.