Stripped spark plug threads 75 Dart
Don't know if they still make them or not but my absolute favorite for fixing plug holes was an actual sleeve.
They were threaded for the plug on the ID and came with a tap for the OD.
Not a heli coil but a solid threaded sleeve.
The only real deal with the heli coil is you have to use clean threads, red Locktite on it and trim the ends smooth after it's installed.
Other than that they have always worked for me.