I have the top end (no pistons) off a 96 polaris XCR 440 SP for sale. Polaris' racing jugs for 96, no exhaust valves. The number stamped on the side is EC45PL 08. It's up on ebay. Link:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180302219653
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180302219653