Oil Temp Sensor and other "sensor" questions 3.0L

[bullethole]

This may be a stupid question, but where is the sensor on the motor used to drive the oil temp guage. Is it the one located on the case half just below the Oil Pressure sensor on the right hand side of the motor (facing the motor from the rear). I ask, because the exploded views of the assemblies call it something else.
What is the purpose of the "switch" (i'm assuming it’s a switch because it has two connectors for the wires on it) on the left side of the motor (again facing from the rear).
I have 3 motors, and each of them are slightly different. On my 83 there is a sensor on the far right side of the cam chain cover, on my 82 and 78 vintage motors this does not exist.

Any help would be appreciated