Have you tried the major tool distributors? Usually Snap-On, Mac, Matco or Proto have just about everything. Most of them even have websites with the tool dimensions such as depth, I.D, O.D etc.
I've got an aviation background (and still in it) and I can't remember anytime they failed to find a tool for me. I've also worked on trucks, tractors, boats, etc.
There are also some off brand tools (Husky and the like)
carried at your local auto parts stores that would also be likely to have the right tool. If all else fails, have one of the deep well sockets machined out a little deeper.
Good luck!