Those horns were made by Altec and are old, but they are not the original multi cell horns. My Father started working out there in1967. I was born in 1971. From 1978 through 1985, I would go to work with my Father a few days during the summer. He would drive me around, so I could look at the Altec system. The original horns were replaced in the early 1990's by the square horns shown in your picture. And those horns were slowly replaced by the small round horns several years ago. Hope this information helps.
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The Horns shown below are the Original Atec Multi-Cell Horns.