Harry had to holler - it's a long way from Washington State to the State of Maine. It would have had to be louder if the wind blew the other way.
I've posted this before - it's a digital picture of a "real" picture of the 105 Cub Cadet that got Jeanne and I started on this journey 18 years ago. Who can forget their first? This one (the Cub) cost $50 because it wouldn't move. Freed up the relief valves and had a tractor! Ended up selling it to a friend who just wanted it to twitch firewood/haul trailer. Stripped it down for him and he took it home. His wife wasn't impressed - until the day he left it parked on his front lawn when he went to work and someone stopped to ask if it was for sale.
I found a champion L87YC on my 64 cub cadet 100 and it's not a spark plug that was ever put in this model. So I brought a champion H10C spark plug and it was to small to fit in the head. So do I have the wrong head or what's the correct spark plug for it.
I'm not familiar with the first plug you mentioned but it sounds like someone may have stripped the threads and just found a larger plug (?). You might be able to insert a heli-coil and get things back to normal.
This is a case where pics could/would be very helpful.
Devin, sounds like someone may have stripped out the threads then drilled and tapped it with oversize threads to fit a larger sparkplug. Any chance you could post photos of the head and plugs?