Finding Models of 2001's, Thunderbolts, and Whelen sirens,

[Ziginox]

The Vortex and 4000 series sirens can, however, be identified via the small protrusion on the rotator itself. If the protrusion is a circle, 4000, if it's a square, Vortex. So far I have never seen these prove wrong. Another thing is the control cabinet: If it's just one small, square compartment, it's a Vortex. If it's a Type I or Type II (I don't believe 4000 series sirens used the Type III), which means that there would be extra compartments on the bottom of the controller, then it's a 4000.

Can you provide any examples of the rotator differences? As for the cabinets, a Vortex will use the cabinet you described, but that is called "Type-I". The 4003 and 4004 use the Type-II control cabinet, which has two separate doors. The Type-III is only used on the larger omnidirectional units. Also, if you check out the 2001 Series page on the wiki you can learn a bit more about what the internal changes were between various generations.