Sorry, i might not have been real clear. The link that you had to Bratton's showing the battery support is all there is. It is a battery support, so not really a "box". If you have the battery support, that came on every Model A frame produced. The battery just sets down in the support. The original battery fit perfect in the support, new ones now are a little smaller so the original hold down clamps don't work as well.
The way I heard it there are only two main lead acid battery manufacturers in America, Exide and Johnson Controls. I run a group 25 no problem
The OEM battery support works fine for the Groups 1 & 25 batteries. The problem is that the OEM hold-down clamps do not work well.