Congratulations on your tractor. That is a great machine, simple, durable, and easy to maintain. You basically have a YM2000D or YM240D but with a few less horsepower and no water pump. I don't think the 1700D was particularly common, but fortunately it is interchangeable for parts with the YM2000, probably the most common Yanmar tractor. It looks like the loader is by Coldwater, also from Washington.
Your engine should have a data plate on it describing the power rating, it is likely around 20 hp at the engine. The Japanese domestic tractors of this vintage were identified by PTO horsepower in their model number. You have a 17 PTO horsepower tractor. The YM2000 is a 20 horsepower, etc. The second pair of digits (In your case, 00) would be used to identify some model upgrade or change of series, I'm not sure exactly what/how. For example, there are YM2001, YM2002, YM2010, and YM2020 tractors that are all rated at 20 PTO horsepower, but they are not the same machine. Your YM1700 is a later version, since it is red and has the square headlights above the radiator.
Welcome to the forum, let us know how you enjoy your machine.