Sensor?

[LET]

I have what i think is a sensor on my 67 gto, right side of the engine between two spark plugs. I have attached a picture of it. I've been searching but can't find it in any of my books. It's common on 400 gto, I've been able to find it in pictures of engines on line. I just received an engine wiring harness, there is no wire for it. Can you tell me anything you know about it?

Second question, i removed my two groove crank pulley today, it's a six bolt. One of the bolts has snapped off. I don't know how many miles it was driven with only five of the six bolts holding it on. What would you do, put it back with themissing bolt, try to get it out, or buy a new harmonic balancer?
Thanks guys,
LET

[Blue Bowtie]

That's right where a temperature sensor would normally be, but that's not the typical "T" style connector used on those. Is this a later engine or heads transplanted into the '67?

The cars that had both a temperature gauge and warning light might have used that type connection, but I think those were in the '70s.