Continuing to track down source of no voltage to coil while cranking

and luckily, a previous owner had completely bypassed the seat belt interlock system, unfortunately they also removed the Automatic Transmission wiring from the car, so I have no reverse lights and have to ground the starter relay.

Well you FOUND it and boy!!! I bet!!! you learned a few things along the way!!!

If you need a new connector at the transmission for the reverse and neutral safety, know that there are a couple of types.
The difference IIRC is the molded step. This is one style. (standard motor parts #S747)


edit: Kunkel on moparts had posted this pic showing the differnet flavors.
Connector above I think is the one one for a '68-77 switch. 2nd from right in photo below.
The one on the right is supposedly '78 up and gets a different connector.