I found this Teletype oscilloscope at a local surplus shop:

https://photos.app.goo.gl/4f2QLgFmnH9tMeYE6

It looks like it was a part of the AN/FGC-5 set for the Navy: 

https://www.navy-radio.com/rtty-mux-fgc5.htm

The owner of the shop (surplusgizmos.com) is usually willing to negotiate prices if someone is interested.