I picked up a second AC over the weekend at a local auction. Its a later model 916 with all its wiring stripped out. There's what appears to be a brand new 1987 Briggs 16hp engine under the hood.
The ignition kill switch, voltage regulator, and headlights have no wiring.
There's a brand new four wire ignition switch, with terminals marked D, B, S, and C. I figured out that B is for battery, and S is for the starter solenoid wire, but I'm not sure about the voltage regulator wire. (The VR has a single red wire, the other two yellow wires are connected to the stator wiring under the flywheel. I also need to hook up the magneto kill switch wire, which needs to be grounded to stop the motor. I've had it running already simply by jumping the starter, the trans works, the hydraulic lift works, and the tires look new. There's a new steering wheel and new upper steering bushing with it as well that I've got to install too.
Also, how did the headlights originally power up on one of these? Its got a headlight switch and two headlights but nothing in between.