I have an original painting of that box top on my office wall, rendered by Bill Campbell, the original artist. (The second version was painted by John Andrews, who produced kits for Hawk, after Bill left the company) He did it for me after I wrote a couple of articles about him for Outre and Illustration magazines. I'll be bringing it to Wonderfest as part of a display in support of my book about Bill. And if you want to build an XAB-1, you still can, as long as you don't mind if it's resin instead of styrene.
www.fantastic-plastic.com/ConvairXAB-1CatalogPage.htm