Identifying Simplex Alarm

My high school has Simplex 4903 alarms. They are electromechanical, but I can’t figure out the model number. Can anyone supply any info to help me? It seems that most are free run, but I’ve seen at least one synchronized with a remote strobe.
If I were to guess based on sound, I would say 4903-9217. They sound more distorted than any 9219 I’ve heard.

The only difference between the 9217 and 9219 is the strobe candelas rating, which really wouldn’t affect the horn…

There is a sticker on the strobe-- older ones use symbols, newer ones use a label.

Nothing or green asterisk: 15 cd
Blue dot: 30 cd
Orange triangle: 110 cd

Also there is no way to tell from the front if it has a sync strobe or not.

Well, I can tell when the strobes are flashing in/out of sync.