Buescher True Tone Clarinet Mystery

  Last week, I overhauled my first Buescher True Tone clarinet and found myself with many questions. Its a wonderful horn - well built of tight grained grenadilla wood and wide, solid nickel alloy keys, with a .595" bore. It has a big, open tone and good intonation (at least with my dubious skills)...but...did Buescher build this thing? Online research turned up no serial number list that seemed to correlate  (the serial # was in the 17,000's) but I did find a reference suggesting that it may've been built by Penzel Mueller on contract!

 Oddly, the build and serial would seem to bear this out: the serial number, instead of being cross-ways on the back of the lower stack, was incised longways on the side. Penzel Mueller was the only company I know of that did this, and the serial would date a PM to the late 30's/early 40's. Keywork seems to bear this out this age range, as the throat Ab/A has an adjustment screw and the LH pinky keys are mounted on separate posts. Also, the wide, flat rings are very reminiscent of PM's of the period. Finally, .595" is a pretty big bore for the period, but most PM Artist clarinets (their pro model) that I've worked on from the period have measured .595".

 Does anyone have information about True Tone clarinets that they'd like to share? This is such a good instrument that I plan to keep my eye out for one and would like to learn more in the meantime. It would be interesting and slightly ironic if Buescher, who made so many saxophones under so many names for others, had their better clarinets made by Penzel Mueller. But, given the quality of the latter's Artist model, I wouldn't be surprised at their choice...