The serial number for the tractor should be somewhere around the clutch pedal or under the floor board on that side. Depends on the tractor though. Should have a bunch of japanese first then a letter and number. In my case, mine says l1501, under that is a serial number for the package, horsepower, and the engine model. Not sure which order is which. You'll need to find the engine model, which mine says z750a. You can search tractordata.com and find which north american model has that engine, and use that model tractor for ordering your engine parts.
If you can find the model number tag for your tractor, we should be able to tell you which north american equivalent you can order engine parts for your tractor from.