Here is a handy web site for finding and ordering the right parts for you John Deere lawn and garden tractor. Just type in your model number and it will give you a list of parts like filters, spark plugs, belts, etc.
This is actually a John Deere dealership franchise located in Dutzow, Missouri with a sister store in Union, Missouri. The dealership is Schweissguth Brothers http://www.schweissguth.com/ who happens to run the Keeping it Green website. Very reasonable on prices. I visit both their stores.