We all here share that hobby!
You'll be surprised - Back then Yanmar built things to be owner-maintained, anywhere in the world, in almost all cases with the simple tools any farmer would already have. The company continues to have a strong pro-ag attitude.
And back then they went to the existing suppliers of the electrical systems on Japanese cars and motorcycles for starters, alternators and regulators, lights, the choice of which battery, and I suppose they used industry-common parts like the clutch assembly. So the parts an owner is likely to need for maintenance are available anywhere, so long as cross-reference info is available. And that's where this forum and Maverick's YTOG are valuable.
These old Yanmars are like old VW's and Jeeps for continued parts support, now by third-party suppliers. The US is only a small part of the world market where these were exported, are still in use, and are well supported.
Some Yanmar folklore you may not yet have discovered: 30-40 years ago refurb factories in VN bought used Yanmars, swapped parts around until there was one complete tractor, applied a museum-quality paint job, and sold them over here. A few were misrepresented as new. Most of these tractors, like yours, then provided excellent service for another generation. Much of this forum was discussion on these.
Yanmar also had dealers in the US that sold US-spec models. Then closed them to build for John Deere for a couple of decades. Then returned to the US more recently - with sophistocated complex modern tractors that don't have much in common with our YM-series ones.