Jim, Thanks a lot for a great idea.
I have been unhappy with my chain storage solution for some time. I even tried to figure a easy way for square tube boxes, but abandoned the idea, because it was too big. I never gave the skinny boxes mounted outside a thought.
I now have 2 chain boxes, very handy, just as I exit the tractor, thanks to you.
I will think, how great your solution is, each time I reach for a chain for now on.