I believe this item for sale is actually a brake drum. I know there is a belt drive pully for the PTO which may look similar, but I'm sure that this is a brake drum.
HR
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2592324020&category=56175
HR
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2592324020&category=56175