It's a 1969 Conn 16M director's model tenor. Most of these horns did have nickel plated keys, but a few were lacquered brass. It's also possible that the sax and keys were relacquered. Your horn was made in Nogales, Arizona. Conn started moving production to Nogales in late 1968, where they produced horns for a few years before moving production to Mexico. The 16M's do sound pretty good. The earlier ones that were made in Elkhart are the better 16M's, but even those made in Nogales don't play too bad.