IS-6 (Objects 252, 253) In November 1943 the work started on Objects 252 and 253, to develop a high power tank. The project's goal was to produce a heavy tank in the IS serie by the name IS-6. A high technical vessel with high power breaks was tested in the beginning of 1944, but a new type of transmission failed. Two versions were presented during the summer with a more classical design and standard of technical komponents, none of them was accepted by the army and the project was shut down.