box, take a couple of pics of that old tractor and post them. It looks like an old Ferguson or Ford. I have a 1957 TO35.
On your carry all I have an idea to think about. Build it atleast large enough to carry 1 kitchen appliance, range, fridge, washer, dryer...whatever. Might come in handy taking one out to put another in. If you build it as wide as your tractor it would be nice too. Could become a portable work bench. Put brackets on the sides (cut pieces of C channel) and then build sides that slide in and out and use it to carry a stack of firewood out of the woods. You'll think of all kinds of uses for it.