Martellus --

I built my Hellcat from a 21st Century Toys Walker Bulldog lower hull. It (and the crew) are 1/18th scale. The track is a rubber band type of thing. Since the dimensions of a real Walker are longer and wider than a Hellcat, the 1/18 model comes out to be about 1/17 scale. I built it long before HL came out with their Walker Bulldog. I wish I had another 21st Century Walker, they are asking big bucks for them on eBay.
rex