Cast iron enameled transmitter arm identification

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I came by this transmitter arm in a lot at auction. It is unmarked but has a nice gold pin stripe on its base. The arm and base are cast iron and thickly porcelain enameled.  The transmitter is beveled and unmarked and looks like another Chicago one I have.  I cannot find a Chicago phone with this type of base for its arm. Can any wood phone collector help me identify it as I am not at all up on wood phones. thank you jc

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Well I found a mark on the face of the transmitter...