I am scanning some catalogs for Mr. Werden, and in a 1968 catalog 100
it has this photo on the back inside cover.
It appears to have a different screen, a combination of the Tic-tac-toe style and the modern style one.
Proud Owner of too many sirens, lightbars, civil defense items, and diecast cars
It could be a prototype or promotional photo where that may be the only one made. I'll keep a lookout. This looks like the tic tac toe board is a screen support. With the older window pane Tbolts the bars were actually part of the horn.
According to the pictures on the cd Clayton gave me, there's at least two Thunderbolts like that in Hamilton County. One is listed at 2465 Little Dry Run Road (roof mounted on a school) and the other is at 8100 Given Road on a pole in Anderson Twp. It looks like they both have a screen over the bars. The survey was taken in 2002, so I don't know if these are still in service.