(Helen) This sax is a real head-scratcher. Whoever built it, it certainly wasn't Buescher—the same Buescher that made the True Tones, Aristocrats, et al.
Pete Hales and I have discussed this horn, and neither he or I really came up with any solid leads on this tenor's origins. Was it made for Buescher by someone? But who? Was there some other company out there using the Buescher name? You'd think by now a few more horns would have turned up. What's interesting is that this sax showed up in Germany. Whatever this sax is, it is certainly an oddball.
(Pete) The closest contender to who made this is probably Kohlert, but the horn has left side bell keys and such an extremely low serial number for Kohlert, that it's really easy to eliminate that as a possibility. It essentially has a characteristic of several makes/models, but some other characteristic says "nope."
If anyone out there has a suggestion, I'd like to hear about it! You can reach me at firstname.lastname@example.org.