In response to the earlier stuff about this being an assault gun or a tank; its mission profile fits in with an assault gun. It was meant to be used to breach bunkers and defences in Japan, similar to German guns.
I to saw this at Knox, man, was that mind blowing! IT WAS ENORMOUS!
'nother question, whats the German tank that is on the trolley next to the T28 on the pic above, it doesn't quite look like a normal KT.
GREAT MODEL! That thing is priceless!