Need help identifying alternator wiring on my RX-7 FC.

The car is a 1986 FC Turbo chassis with a 1991 Turbo engine swap. It currently has an FD-style alternator that uses a 2-pin regulator connector.

Years ago I cut off the alternator pigtail because I used it on another FC. I specifically remember cutting what I thought was a 2-wire alternator plug.

Now that I’m putting this car back together, I found a cut cable in the alternator/starter area that contains 4 wires (red, green, blue, and tan/white) plus a shield braid. The cable runs alongside the heavy alternator charge cable under the same loom all the way back into the harness.

What is confusing me is that all FC wiring diagrams I can find show the alternator using only 2 wires (typically Black/White and White/Black), and I have not found those colors anywhere.

I also found several listings online for “86-88 RX-7 alternator harnesses” that show a 4-wire connector and ring terminal assembly, even though the alternator itself only has a 2-pin connection.

My questions:

1. Did the S4/S5 FC alternator sub-harness actually contain 4 wires even though the alternator uses only 2 pins?
2. Is there a separate vehicle-side charging harness on FCs?
3. Has anyone seen the factory alternator harness wire colors match red/green/blue/tan with shielding?
4. Could this 4-wire shielded cable actually be part of the original alternator harness, or is it more likely related to another engine sensor/aftermarket ECU wiring?

Any pictures of an unmodified S4 or S5 alternator harness or wiring diagram excerpts would be greatly appreciated.