Only a complete stupid idiot would design a spark plug with 5 or 6 exposed threads in the combustion chamber where carbon can built up. And I really don't give a dam about the spark plugs, what you really care about is wrecking the threads in an aluminum head.
My kid believed that BS about plugs lasting 100K miles, but was getting misfires at 60 K, told him to add three cans of Seafoam to his gas tank, 24 gallons on these things, that softened up the carbon so we could ease them out.
Have no idea why Chrysler uses those mile wide upper intake manifolds, all the air intakes are on the center, but they had to be removed first. And their coil on plugs did not have those rubber boots that baked on.
KD makes a spark plug hole repair kit, had to use that on some cars, this never was a problem with cast iron heads.
On some cars that carboned up quickly, put the plugs in my machine lathe and cut those worthless threads off. If you really do a search can find plugs that are made that way, but may take you a life time.
Kind of hate Fords, they use unplated raw steel rolled bolts in aluminum, stupid basterds never heard about electroplating with different metals. One little tiny pull with a hand wrench, the heads break off. Took me from early morning to passed midnight to replace a water pump with broken bolts. Drilling them out was not a problem, but removing all that crap blocking them was.
