I changed the spark plugs on my newly acquired Ranger and found what I believe to be OEM plugs as NGK iridium. I replaced with Motorcraft double platinum. I had a hell of a time removing the spark plug boots, never experienced anything like it and I've been changing plugs for 40+ years.

 

Yes, that would be odd, Ford used Motorcraft as OEM, so probably not original, NGK are a popular choice for replacements

What year and what engine?

 

2011 2.3l

 

OEM were Motorcraft SP-439 and SP-439-A, gap 0.044, or AGSF32FEC, gap 0.054

Because it uses waste spark, 2 plugs will have coated centers and 2 will have coated tips, instead of just using double coating, just cheaper when buying literally millions of spark plugs a year, lol

 

After researching on this site, other 2.3l owners have also found NGK iridium plugs, which they believe are original to the vehicle.

 

Well the problem with that is "Motorcraft is an auto parts brand owned and operated by Ford Motor Company"

The 2.3l Duratec is a Mazda L engine, so not a Ford engine, Mazda did use NGK as OEM(like Ford uses Motorcraft), so, NGK is technically OEM for this engine, and fine to use
Wouldn't surprise me if people did find NGK spark plugs as "original" in the 2.3l Duratec
But factory spark plugs spec'ed by Ford would be Motorcraft

Ford had a big stake in Mazda from 1974 to 2015, and used several Mazda designed engines in Fords, and I am sure more than a few came with NGK spark plugs installed when they were assembled
But Ford always had Motorcraft spark plugs spec'ed as replacements, just not worth the money to swap then out during assembly