Final answer:
The ground power receptacle on the MD-80 is situated forward of and below the cockpit, essential for connecting external power sources for servicing.
Step-by-step explanation:
The ground power receptacle on the MD-80 aircraft is located forward of, and below, the cockpit and nose of the aircraft. This enables ground crews to connect external power sources directly to the aircraft when engines are not running, allowing the plane to operate its electrical systems without draining the aircraft's own power supplies. It's a critical component for aircraft servicing and maintenance.