Those heavy tanks were part of a heavy tank project T-28-34 from 1943-48 with the primary purpose of the invasion of the Japanese homeland. Since the bomb ended the war, some of these tanks, like the T-30 you submitted were retained as test vehicles. the T-30 engine pack, Continental V-12 810 HP with Allison CD-850 transmission was used to upgrade the M-26 which became the M-46 Patton. We have one of 4 existing models (out of 8) at Ft Jackson, and I just finished installing a set of periscopes in it. Next week I am going to clean up the rammer mechanism and crane for an article being written here. The T-28 super heavy is the only example of two and it's at knox. The T-30s sister tank, the T-34, developed into the 120mm Gun Heavy tank M-103 which was used by the 33d Armor in Germany and upgraded M-103A5s served longer with the Marines. Danville Tank museum has one of the very rare later models. With the extraordinary weight and severe restrictions on maneuverability, these tanks were never programmed for tank vs tank war in ETO and would have suffered the same fate as the Jagttiger, king tiger and Maus of being resticted to the nearest bridge.