All of them had the option for a center coin slot.
If you look at the cabinet wiring schematics you will see that pin 9 of 7P1 is for the center coin slot.
If the coin door did not have a center coin slot connector 7J1 did not have a wire at pin 9.
All of the coin switches, the slam tilt switch, and the high score reset switch are tied to a common return at pin 5 of 7P1/7J1.