Comparing: IS-6 vs. KV-5

Plans for this vehicle were drawn up in the construction bureau of the Chelyabinsk Kirov plant from December 1943 to the summer of 1944. Further development and the construction of the first prototype took place at the Uralmash plant. However, the vehicle had no advantages over the other heavy tank designs under consideration, and its armor was seen as inferior to the IS-4 (Object 701), so the IS-6 was not selected for production.

Development began in June 1941 at the Leningrad Kirov Plant and was completed by August, but plans were interrupted due to the complicated situation on the front. The KV-5 was to utilize some components of the KV-1. A new turret was designed, incorporating the 107-mm ZIS-6 gun. Two roadwheels and a single support roller were to be added on each side. A new 1,200 h.p. diesel engine was being developed for the vehicle, however it was not completed in time and was replaced with two V-2K engines.