Ben, gray market tractors are those that were not specifically made for the US market. Most were used on Japanese farms for a while and then purchased by a stateside independent importer/dealer. Most of these don't come with a ROPS, PTO shield, user manual, and safety labels in English.There's really nothing "wrong" with them, except most authorized US dealers will not support gray market units. Accordingly, these units can usually be had at a substantial discount. Kubota has a list of gray market tractors on their website at http://www.best-used-tractors.com/gray_market.html. If you can find a comparable US marketed model, parts will probably be pretty easy to come by. Someone correct me if I'm wrong, but from what I've seen the Yanmar and Kubota gray units are most likely to have an almost identical US counterpart.