Here are some pics. First pic shows my original panel on the left, with RPM Transducer and Rear Defroster Relay still attached. The empty socket is for the Starter Enrichment Relay, which I don't need. I pulled out the harness, intending to install it into the 84 panel, on the right.
This pic shows the end of the Motronic harness, which I believe attaches to the control panel. This socket is the one I'm curious about. I believe it is the same one in Motogman's photo as well. As inaminit noted, maybe this is the test plug, which would go into the round hole on the vertical panel of the 84 control panel?
I should add that I already purchased the replacement O2 connector from a fellow Pelican (can't remember his name now).
Roger