Just a note if you happen to own a 1981 to 1995 Jeep with the inline 6 engine.
Your spark plugs are gapped at .035″ and are single anode. Do not use double anode.
However, they will work gapped to .045″, and the dead one was gapped to a frightening .051″.
Don’t trade your jeep for the world, and it will run forever for you.