The single terminal brass unit is a thermistor type sending unit, it will operate a gauge, the 2-terminal "switch" in the manifold is a liquid temperature switch for an idiot light or electric cooling fan or emissions control. I can't make out an oil pressure sending unit.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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