Comparing: IS-3A vs. O-Ho

In 1956–1957, the Military Armored Forces Academy developed a speculative design for a new loading system on the IS-3 and T-10 heavy tanks. The IS-3 variant featured a double-row ammo rack with an automatic loading system. The crew was reduced to three members: commander, gunner, and driver. The turret was redesigned in order to accommodate the loading mechanism. The vehicle existed only in blueprints.

The O-Ho was a further development of the idea of a superheavy tank with improved armor protection. The vehicle had a good set of guns that allowed for all-angle fire. The project was discontinued due to the war ending. No finished prototypes were built and the vehicle never saw action.