Dave,

There are a few sources that should be able to help you out. You could try O'Brien County Implement, <!-- m --><a class="postlink" href="http://www.obci.net/">http://www.obci.net/</a><!-- m --> or Maibach Tractor <!-- m --><a class="postlink" href="http://www.agcocorpdealers.com/MAIBACH/">http://www.agcocorpdealers.com/MAIBACH/</a><!-- m -->

There is a guy on ebay that parts out tractors, and he has a 77 all stripped down and on there now, including the parts you need. <!-- m --><a class="postlink" href="http://shop.ebay.com/merchant/marty2374">http://shop.ebay.com/merchant/marty2374</a><!-- m --> and then type Oliver into the find box. He is located in Michigan, but I don't know him from Adam, and have never bought from him, so I can't say how good his parts and service will be.