Look for the HIN (hull identification number) on the outside of the transom. These are usually on the upper portion of the starboard side. The initial characters give the manufacturer (which you already know is Four Winns) and the last two digits are the model year. Regarding what model it is, I haven't a clue.
I should have the hin in the next day or two. The seller was out of town and did not have the title (or boat) handy. He's going to send me the info when he gets back. Until then, I'm just trying to figure out exactly what it is and get a ball park of it's value.