I have several of these light guide displays for sale. They use a light guide for every single digit. On the back of the device are several small bullet-shaped incandescent bulbs that can be swapped out for LEDs.
One just sold on eBay for $100. I can't guarantee that all of the bulbs are working so I am asking for $50/each.
In absence of connectors, what is on the back of the display units? Are the bases of the bulbs exposed or are the bulbs fully enclosed with some sort of pins / mating connector sticking out the back? IOW, is the missing connector piece actually part of the bulb sockets or is it just a connector?
Look into it later when the dust is clearing off the crater.