The keywork on most of the early Bueschers is virtually identical to the Conn models of the same era (keys on the same side of the horn, etc.), probably due to the fact that Mr. Buescher used to work for Conn -- and one of the owners of Conn was on Buescher's Board of Directors for years. The True-Tone horns may have a similar look to a Conn, but they have a darker sound, no rolled tone holes and lighter key play. the serial number you have I believe points most closely to 1923. These are great horns, and in good shape are worth a bundle.(mint it would be worth $900 fer an alto, 1200 fer a tenor)