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183-4u. Years in production? No idea, but they were made with both clock springs and later the plastic ball joints so, at least a few years. Fun horns but imo a 180 in Eb (some off notes, singing upper register, crappy low end)

I agree that this horn is a 183 but I've only seen factory detachable bells have been recording bells. My guess is that someone used the recording bell flare and ferrule, fashioned the straight section, and put stuff back together as an upright bell.