I'll take a pic tomorrow evening. There are two studs on the circuit board right below the oil gauge that accept the same nuts as the two studs they belong on. I think they are grounds for the circuit board.
I think you are going to learn tjose 2 studs are the Oil gauge mounting/contact posts. They would have the same stud threads but the nuts were supposed to be different from what was used on the ALT' gauge.
After nearly 50 years who knows what nuts you might find.