oil sending unit questions

The unit below the distributor is an oil pressure sending unit, which operates an oil pressure light.  The unit at the bottom of the engine is an oil temperature sensor that activates the oil temp gauge found in the fuel and oil temp gauge cluster.

I'm not sure about the gizmo in you hand, but  it appears to be a sending unit for an oil pressure gauge, which you don't need if you intend to operate only an oil pressure light.

Jason

You're right on the first two, Jason.

First pic is indeed a temp sender, they are available still and are custom for the dual-relief case on the pulley end. There is a spring and an oil control piston above the sender which MUST be there.

Second pic is what I call an idiot light sender, it is a pressure based switch, I think the switch closes under 8-10 psi, illuminating the dash light.

The third sender that's in your hand looks to me like a VDO temp sender.

Thanks @JasonC @DannyP