There are two 1/4" NPT tapped holes in the 300 block towards the rear, one on the left side and the other on the right side.

Believe one is for oil pressure and the other of oil temperature or coolant temperature? Original sensors were electric wire.

Replacing with mechanical output sensors.

Looking for the block location for the oil pressure , coolant and oil temperature.

Maybe the coolant temperature is measured at the themostat housing on the cylinder head?

 

On the driver's side there are two tapped holes that both go into the lifter galley. You can use the rear, the oem location, for oil psi, the other for oil temp. The tapped hole on the passenger side, toward the rear, is coolant. I use it for running temp. If you use the thermo housing for a temp sending location, your reading will run about 20* hotter than reading you would receive from the passenger rear block location.

 

Is the drivers side forward block port normally factory plugged?

 

Engines with an EEC use the coolant port in the block for the gauge panel and another fitting in the water neck for the EEC temp sensor.

 

Yes. It is factory plugged.

 

There are two 1/4" NPT ports on the right side.
Understand the rear more port is used on coolant temperature.

The forward port is plugged.
Is this a coolant drain plug?