hmm idk, this game is not accurate but if you replace the infamous t-34 "MEDIUM TANK" with a KV-1 "HEAVY TANK" it would difine the Red Army in the opposite of what it truly was , Fast and Vast. T-34s were the mainstay of the Red Army, so I believe that the KV-1 should replace the su-100 or the IS-2. ( which can be later upgraded to be equivilant of the IS-2, )