https://www.youtube.com/watch?v=tTyY2bMvDDs
Watertown, WI used to have multiple Allertors. They were all 9-12 port although some of them had the older, smaller horn. The siren in the video has the larger exponential horn. General age of Watertown's Allertors would span anywhere between 1971 and 1984, a bit later than the video estimates.
As a "bonus", here's an old Google view of the smaller horned Allertor. It was replaced with a leftover SiraTone 1212.
