Pre-soldered jack, push-pull pot, with a capacitor.

To connect a push-pull harness to a Box Bucker Gen 2 or any other split coil pickup connect as follows. There is a long black wire which is the ground wire for the bridge. The shorter black wire includes a white lead that goes to the hot on the pickup , the bare jacket wire goes to the ground from the pickup.  The center tap wires, usually red/green  connect to one of the top tabs on the switch.

Push the knob in for humbucking and pull out for single coil.