When I first purchased my truck, I bought the GI type lug wrench, with the cross-bar and double ended wrench. As David mentions, they are not uncommon, as the Budd wheel design has been around a long time. Kentool actually still makes them.
http://www.kentool.com/index.php/produc ... nch-detail
The charm, however, of using this tool to remove wheels was fleeting at best, so I relegated it to the truck's tool kit. For working in the garage, I bought the exact socket that Bill references, above. It actually has both the hex and the 13/16" square drive incorporated into one socket. Once you remove the hex nut and outer wheel, the socket slides on far enough to engage the square top of the inner nut. it works great, except when removing the front lug nuts. Mine always seemed to want to engage the hex nut, which would loosen up first, then you had to go back and remove the inner square headed nut.
So, I finally purchased a separate pair of sockets, one for the outer hex nut and one for the inner square drive nut. If you do an ebay search on "Budd wheel socket" you will get tons of hits. Used sockets are actually quite reasonably priced.
Best Regards....