What sirens I've seen (my own list):
Federal Signal: 3T22A (Emmitsburg/Rocky Ridge/Thurmont), Model 2 (Fairfield), Model 5 (Gettysburg/Thurmont), STH-10 (Gettysburg also).
Whelen: WPS-2905 (Emmitsburg).
Sentry/Sterling: M-10 (Taneytown).
That's pretty much all the sirens I've saw.