As far as the sizes, they did make 2 different ones. One fit the old 400, and believe it or not the old 300, the other size was the more standard one that fit all the other full size cat 4-wheelers. I bought one on e-bay from a guy here in the UP 2 years ago for 200.00. They are nice but they do have their limitations. For instance, the set-up isn't particularly fast by today's standards for ice shacks. I have a cabin style (eskimo pro) that sets up quicker, and of course the flip style shacks are much quicker. The other thing is the mobility once you are on the ice. Once set up, if you want to move, even just a short distance, you have to entirely pack up the shack into its zippered cover, or part of the shack could get caught in the wheels when you move, which wouldn't be a good thing!
Another thing to mention is that the shack is held in place be aluminum "spreaders" (6 of them) that clip on to the shack's structure with plastic C-clamps. There is one C-clamp mounted to each end of the spreaders, but they tend to come loose in the aluminum tube (spreader) that they are mounted in. In fact, one of mine was completely out of the tube when I got it. I ordered a few extra spreaders and used a metal punch to secure all the other C-clamps better in their tubes.
All that being said, I do like mine. There are times that it is much more convenient to carry a shack on your 4-wheeler instead of dragging one. And it is something out of the ordinary, so there is a "cool" factor too. But if I could only own one ice shack, it would not be this one, it's just too slow and inconvenient to move around on the ice compared to others.