Take a picture (and post it) of your passenger side valve cover (the portion of the valve cover that is closest to the front of the engine). You can see the sensor in the pic below - it is just to the left of the top f your vertically mounted glow plug controller. See the small red arrow pointing at the sensor.

If it isn't there, then the engine is in fact an '03 engine.

 

Thank you for simplifying that for me! I'll get it tomorrow

 

Thank you for this too

 

Glad to help.

 

Hoping I got this right
If I did this right, could you recommend a brand of harness. My friend told me Motorcraft ZD31 for the glow plugs

 

The ZD-13 is the newer (shorter) glow plug.

Also: 4C3Z-12A342-A

 

Ford dealer have me these part numbers for the plugs based on my vin
Ford 3C3Z12A342A and motorcraft ZD31. Did he transpose the Motorcraft?

 

3C3Z-12A342-A is the SHORTER glow plug. It should be ZD-12. See the on-line dealership list in the link below:

https://www.tascaparts.com/oem-parts...ug-3c3z12a342a

• Genuine:
  
• SKU:3c3z12a342a
• Description:F350. 6.0l diesel. To 9/22/03. Excursion. 6.0l diesel.
  
• Applications:1999-07 SUPER DUTY.
• Replaces:3C3Z-12A342-AA, 3C3Z-12A342-AA2, ZD-12-, ZD-12-2

Ford does sell a ZD31 glow plug, but it is on back-order and I think that that number is a mistake and doesn't apply to the early 6.0L. Yours needs the ZD-12 based on the 3C3Z-12A342-A number.

https://www.tascaparts.com/oem-parts...glow-plug-zd31

Let me get the exact lengths of each glow plug for you, but since yours appears to use the long one, then probably not a big issue.

 

https://www.powerstrokehub.com/servi...plug-test.html