Re: mystery conn usa - question for jim?
The Conn 22M is one of the later student model Conn tenors. They were made in the US after Daniel Henkin bought Conn from MacMillan and moved the company back to Elkhart. The N prefix is for 1970. By the end of 1969, MacMillan had closed the Elkhart factory and moved production to Nogales, AZ. A couple years later, they moved production across the border. This horn was probably made in the late 80's or early 90's. It's basically an updated version of the 16M Director's model.
The new 37M is made in Taiwan as is some of the newer student model Selmers and many of the less expensive horns sold by Conn Selmer. I did play a 37M a week ago though, and for the money, I was impressed.
The 22M is not a particularly valuable horn. Even in good condition, $600-$750 is top dollar. They're actually a pretty good student instrument though.