I have a Holton Collegiate bass sax serial 288xx. The horn has many construction features similar to Conn basses; x style body to bell brace, pivot screws in many locations includunig a pair of combined rod -pivots for the top stack. However this horn is keyed up to F3 and has a right hand C to D trill key. I have heard that mostAmerican basses stencils were Conns. Is it possible Holton made their own basses. I wish I knew how to attach pictures here.