Been a long time. It's either the cruise control stick connector, but probably the VSS, vehicle speed sensor, for automatics, that plugs into the back of the speedo.
It's the VSS on an E4ME CCC controlled system (they are blue, the 82s are yellow) and it's used for lockup control. It goes nowhere, the cable with optical head plugs into the back of the speedo secured by a screw, the other side goes into the ECM harness.