In my humble opinion the JUMBO could be used as a heavy, the uparmored Sherman AKA Thunderbolt VII, would still be medium because it wasn't completely uparmored as the JUMBO hull and turret was. My 1st Sherman has the same armor PKG as T-Bolt but I run it as a medium.

IF I build a JUMBO, I plan to run it as a Heavy at DAK. Rank has its priveleges.