Yeah, the parts store is not the best ever. But I've been to a couple now. The problem with the books is someone has to know how to use them too! Used to be the problem with the computers, now its the other way around. The Riebes I just went to had a crap load of books, but they never opened 'em.
There are a couple of things that are a little goofy about the box. It actually bolts to the plate in that picture, not the framerail, so it was originally designed to be on the inside of the framerail (of whatever it came off of). Also, the output shaft is really long, and all of the mounting tabs are actually on the output shaft housing. It actually looks
a lot like a Ford power steering box, except the mounting is backwards, and so is the bolt pattern.
I'm still looking. I've got threads on a couple of truck forums, maybe I'll get lucky. I'd just replace it with something else if I didn't have to mess with the rest of the steering set up too (also custom).