[COFF] 52-pin D-Sub?

I work at an astronomy facility. I get to do some fun dumpster diving. I recently have pulled out of the trash a plugboard with a male and a female D-Sub 52 connector. 3 rows of pins, 17-18-17. I took the connectors off the board: there's nothing back there, so this thing only ever existed so you could plug the random cable you found into it and its friends to see what the cable fit. I can't find much evidence that a 52-pin D-Sub ever existed. Is this just Yet Another Physics Experiment thing where, hey, if your instrument already costs three million dollars, what's a couple of grand for machining custom connectors? Or was it once a thing? (also posting to cc-talk) Adam