Hi Guys
Hanno is right its defiantely a Marmon Herrington tank of some kind i was looking at the drive sprockets and they look a lot like the Marmon-Herrington Tracked Jeep sprockets on this page :
http://www.geocities.com/marmonherrington/tractor.html
So i wonder now if its a bitsa using a box of army surplus parts maybe ?
cheers Plushy