Where does this wire go? Found under oil filter.

My 63 Valiant never had a cover on the oil light wire, either. Nor did the 62 Polara 500 convertible my parents owned when I was a kid. One day, maybe 1963 or 1964, I was cleaning on the motor. Next time Dad started the car the oil light came on. Neither of us had any idea why. Took it to the dealer, guy reached back, hooked up the oil pressure light wire and - Presto! - it was fixed.

My 67 Barracuda has an oil pressure gauge, and it does have a plastic cover over the wire to the oil pressure sending unit.