Good DME Ground speed indicator aeronautic navigation

Wonderfull ground speed indicator dropped from a plane 15 years ago, it was working at that time, but it has been reformed in France. Please don't use in a plane without checking it's fully working. The brand is RCA and there good is a label with 1972 written. ideal to build a cockpit. I have a lot of similar items, let me know if you need a special build for a movie scene or other request.