OK as promised, here are the photos. You will note that the box has a somewhat unusual mounting method; the brackets to the left and right do not connect in the middle; the box wedges into the brackets via a groove running along the back of the box; the box is then secured using the thumb screws. Once secured, the whole system is quite rigid. At first, I was going to replace the thumbscrews with regular hex bolts but then I thought it might benice to remove the whole box of tools and bring them to the front of the tractor, for example to perform a repair...
Anyway, here it is, let me know what you think!