John, WELCOME! As mentioned, C.C. Specialties has a great selection of parts, also R.F. Houtz & Sons, see colored boxes at the top of the page, has used parts. We have a classifieds section here that is definitely worth posted a wanted add in, as lots of forum members have spare parts they are willing to sell.
Welcome John. I am new here as well and have found a bunch of great help here,from the people, the papers.....(manuals, pictures, and parts diagrams) Probably one of the best searches I have ever done on the internet!
Welcome, and if you don't care about the tractor being 100% factory correct, you could always turn one on a lathe. I made mine out of some oak scraps I had laying around. My machine, being a hydro, needed three made. But they are very easy to turn, and would make a great first project if you don't have a wood lathe, but know some one that would let you borrow theirs for a couple hours.