I just finished rebuilding the motor of a 1992 Z 28. The engine had already been out of it when I got it. I noticed on the alternator that there is a plug for wiring harness. This is plugged in. There is also a post and nut on the back of the alternator. I can't find any loose wires nearby that go to this. I checked a wiring diagram and it appears something goes here. Am I reading the diagram incorrectly or am I missing a connection? If am missing something where might it be.