73 duster electrical

I have a wiring diagram the problem is were does the harness [trans] plug into. the harness I have from the trans has 4 wirers 3 of them go into a 3 prom grey connector other wire goes to starter soliniod.also the bulkhead connector on the firewall has 3 slots2of them are plugged in [facing the front of car] left,center. right side is empty,I have a wiper harness that plugs into it. there are 4 wires on one side empty on other. Ihave no idea on what to do? diagram is making blind !!!.