There is another of these sirens in the GA section of Siren Archive; it's Smyrna #2.
I moved from Cobb County(where Kennesaw and Smyrna are located) in 1989. However, I don't think either of those sirens was in place then.
The city of Smyrna has its own siren system; mostly STH-10s.
A number of years ago I did get a confirmation from someone at Whelen(the e mail or whatever has gone by the wayside) that this is definitely a Whelen siren.
The Smyrna siren is nearly invisible, because the speakers are hidden by trees as one approaches the siren on Ridge Rd. I only knew it was there when I saw the control box and happened to lookup.
I've never seen this type of siren anywhere else.