From a quick Google search I read it was manufactured by GardenWay and they went bankrupt.
As others said before me: All trails lead to the big "unavailable".
MTD lists it as "No longer available"
Apparently it was a $250 part, so that's quite a chunk of change to drop into a used machine. I suspect your only option is finding a used one. It was widely used, so probably a shop would have one in it's graveyard of junked machines. Try e-bay also....Ya just never know.
I feel for you, buddy. Sucks when this stuff happens.
Wow! There's been quite a run on these coils lately. You're at least the fifth or sixth person on the forum to loose one in the last couple of months. Check through a few of the threads on the Bolens sub-forum (Troy-bilt/Garden Way tractors were Bolens designs) for more info.
I lost my coil about a month and half ago and went through all the online sources. There are always a few complete PTO assy's on Ebay but they are over $700. There was a used coil on there as well with no idea of whether it was good or bad as the seller wouldn't even give a resistance reading that went for $75. Sunny's didn't have the coils at the time and didn't know if they would be getting any more in though it would be a good idea the check with them if you can get anyone to answer the phone. I ended up buying my coil from member BHTS on here. It was the last one he had but he is trying to track down some more for several other members.