This is a classic Horizon Situation Indicator (HSI) unit, which displays heading and DME data. The unit is made by Sperry featuring its original dataplate and overhaul certification from 1986. This is a beautiful rare classic gauge which is large, and heavy.
These gyro HSI units are increasingly rare and are from the classic age of aviation where flight instruments were individual gauges rather than screens. You are looking at a true piece of aviation history which lots of potential for integration into your flight simulator.
Any work to restore the unit would need the services of a simulator technician to restore the internal servos etc. The unit also features two DME digital readouts for miles to the landing airport.
All rear cannon plugs are in good order, however the unit has not been tested and is therefore sold as is.