'65 Dart temp gauge / wiring questions

Hello!

Can someone tell me what the color of the wire for the temp gauge sensor in the engine compartment?

On my recently purchased '65 Dart (slant 6, 3 on the tree), the PO installed aftermarket gauges, including a temp gauge. The temp sensor would not fit into the original 1/8" NPT hole in the head, so he used several fittings to make it work, but the sensor is so far removed from the coolant that the gauge doesn't work.

I'd like to reconnect the original temp gauge. The engine compartment wiring harness was loosely wrapped in electrical tape, and I found 2 wires wrapped up in the harness that were unused. One was the oil pressure light, which lit when I grounded the wire, and the other is a blueish wire that has no current flowing through it, and none of the factory gauges move when I ground the wire.

Is that blueish wire the wire for the temp sensor? The length puts it right about where the sensor would be, but I want to make sure before I start connecting things.

As an aside, I'd like to use the aftermarket gauge as well, so I'm going to drill and tap the thermostat housing for the aftermarket sensor.

Thanks...

Chris