I have one of the these too. They were standard IBM IO Selectrics, modified
electrically for what appears to be use on a military aircraft. I'm planning
on building
a serial or USB interface for it so I can use it as a remote terminal for my
IBM 1130
simulator. I've gathered a lot of information about it including the
connector, signals
etc. If you're interested, let me know and I'll send you what I have. These
machines
being sold on eBay, by the way, are in wonderful shape mechanically but most
likely
have a shorted or open control soleloid.
Brian