I saw this engine on ebay. The seller says it is a 3.8 prototype engine. I don't know how you would know if this is true or not without disassembling the engine. Maybe you could pull a spark plug and do some sort of actual displacement test by rotating the engine. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33615&item=2424111690