I have a 1947 KB-1 that has 4 square holes in the bed side that appear to be factory. The consensus of the many I've asked is that they're for a spare tire mount. The lower holes are below the bed floor. I've seen many home-grown variations, but nothing that would fit this pattern. If you have a KB with a side mount spare, could you take some photos of it for me? Or if you have one that you're not using, I'd be interested in buying it.