You may have to call to find a dealer. Most around here sell them, but I'm not sure where you're located. They're very good to work with.
http://www.tractorseats.com/p-47154-jd-combine-mud-scraper-sts-series.aspx
http://www.tractorseats.com/p-47154-jd-combine-mud-scraper-sts-series.aspx