Since this is a DFW sirens question. Here's some info.
McKinney, Texas: Whelen 4008's, one vortex, and some Omni directional ones. (Can't remember the name).
Dallas: All Federal Signal SRN-2001's (Some Inactive T-Bolts)
Princeton, Texas: ASC-T'121's
Allen, Texas: ATI's
Frisco, Texas: Whelen Vortexes, Omni Directionals, and a few ATI'S that I hopefully assume they are getting replaced.
These towns are all on the Northeast/North part of DFW.
Hope this helps you!