Hallmark Medalist by York???

[ABQtuba]

In a swap, I acquired (along with an instrument with actual value) a 3-valve Eb sousaphone whose bell reads "Hallmark Medalist by York" and which carries a 5-digit serial number starting with 22. I suspect this horn was made by a successor to the real York company--perhaps in that post-WW2 period when "Yorks" were being made in Germany. If anyone knows anything about this strange beast, I'd like to hear.

Also, if anyone wants it, it's for sale. It looks like a veteran of some junior high school, but it is playable as is and would be even better with a leadpipe brace soldered and its valve felts replaced. Main tuning slide and all valves are free but valve tuning slides are stuck.