I've played about a dozen Mark VI tenors and own a 1961 model. People say there is a lot of variation in these horns, but I don't hear myself any differently from one to another. The 180,000 and up serial numbers may well be less desirable, so I've heard. I have not played one of these. As far as price, the late 5 digit serial numbers (appx. 1957-1962) seem to command the most. Even though I own one, if I needed another, I might go for a mid- 1960's model to save some bucks. But being the vintage horn snob that I am, I'm just jonesing to get my hands on a Super Balanced Selmer. The key thing is to try out whatever horn you are considering. Try as many as you can. Take your time and be patient. Buy the one you love. Take care of it and keep it for 45 years like I have. Good Luck.