The Serie III would be the newer model. You can find out about manufacturing dates on the Selmer website - I think it was www.SelmerParis.com or maybe just www.Selmer.com In fact, I guess they are still using that Serie III designation for a current line of Selmer - Paris horns. The key thing is to try a horn before you buy. There are lots of great saxes out there and a whole lot of questionable brands too. Good Luck.