Roger Holmes wrote: I checked at our radio museum yesterday, but no luck. We have dozens and dozens of Jones plugs and sockets, largest I found were 24 (3*8) and 33 (3*11) pin. The 40-pin requirement is pretty unusual. 4,6,8,10,12,15,18 pin are very common, popularity starts to drop off sharply after that in IME. It might be possible to trim & combine a combination of some more common plugs to fit, particularly if the the actual needs for the task don't require all 40 pins. Worst case, it is possible with Jones connectors to break a plug body (if male pins) to remove individual pins, solder wires to the pins, apply heat shrink insulation and then insert the pins one by one. A current Cinch-Jones catalog from the web shows connectors up to 33 pins. Either the 40-pin has been dropped over the years, it was something special for IBM, or it's not a Jones connector but something close/similar.