I thought I knew, but it looks like the design of the ect sensors changed. The photo 2 is what I knew and from rockauto photos. I keep getting this part -photo 3. Are they the same? The connector connects.
I assume photo 1 is the sender to the temp gauge?

Aside, please identify this box. ECM? It is under the steering wheel (a little to the right and under the dash). I haven't looked behind the driver's kick panel, but there is no bunch of wires going behind the kick panel, or even in the general area.

My truck is 1996 4.9L california emissions.

Thanks in advance.

 

Picture #1 IS the ect that goes in the thermostat housing... it is a 2-wire sensor.

Picture #2 could be the ECU as some kick panels leak and water shorts the ECU. design flaw.

Picture #3 shows the Coolant temp sensor on the left and ect on the right... coolant temp sensor is at the rear of the head over the exhaust under the intake manifold right above the starter....

the pic1 and pic3 show different sensors... you could have a mid year 95 sensor...

 

Thank you for the information.
I thought ect is called sensor and one for the gauge is sender, but it looks like they are used both ways.
The photo 1 with gray plug has 3f1z-12a648-a. One part shop i.d. this number for 1994-2003 7.3L diesel.
The white plug sensor (familiar with this) is f5af-12a648-aa.
Rockauto lists both numbers for 2006 Freestar 4.2L v6.

I'll try using it and see if I get ect reading from obd2 program. The gray plug screws in and connects.

If it works, I did amazon wrong.

Anyway, thank you.

 

I believe mine on the 4.9 is white... they may be different values. there IS a test sheet with voltage values at a certain temp so you might want to google ECT test values and find the sheet and test procedures.

I am sure they use both sensor and sender as terms but you would be correct... it is ECT Sensor and Coolant temp Sender... but auto parts stores list them both as Sensors.