Depends on what you need. If it's tune up, or oil filters, etc., try O'Reilly's Auto Parts. I see there is one in/near International Falls.Stores Near International Falls, MN | O'Reilly Auto Parts
The same C159 Fram filter they want $11.50 for, you can get at O'Reilly's for $7.99.
The trick to finding parts, is to use the OEM part number. If you don't have a source for part numbers, go here: AGCO Parts Books
Enter as a guest user. Enter your model number(B), and manufacturer ( Agco Allis), then hit search. On the next page, scroll to the bottom of the page, and click on B/B/C tractor Power unit. On the next page that appears will be a list of every component of your tractor. When you click on the component of choice, it will go to a page showing an exploded view of that component. To the right, will be a description, and the part number. You can copy that number, then paste to a search engine, or auto parts store site in the search block.
If NAPA, or O'Reilly's don't carry the part, you can always search on the internet through a search engine. I have the best luck using Google. You can literally shop for hours there.