They didn't record or post them, so no there is no source to point you too.
Model years of older Kubota tractors wasn't of much concern to them, as tractors in Japan have a one year life and no more, they either get a new one every year or they are taxed very high for keeping them!
So to them they are always a year or less old.
Now as for parts, year doesn't matter it's all in the serial # for what parts it would need, there is usually very few parts changes mid model and the changes will usually allow and older part to work with the newer part.
And as far as sales Model # and hour are good indicators.