Today the college Fine Arts building staff let me have a couple of alarms out of their box of old fire alarm parts! (They also have an old Simplex clock there, but it was broken.) Here is what I have so far, and I plan to soon add more to the collection once I have the money. And I only plan to display them, not set them off (like TrueAlertSS and Firefly usually do).
Faraday 6020 horn. This is the same kind of horn as the Simplex 2901-9833. It is rather old, and has a bit of paint chipped too, but I'm sure if I tested it, it'd sound fine.
Tag on the horn.
Unusual retrofit plate of some sort. It may be a Simplex model, but it could be Faraday's knock-off of the 4050-80. It's the same size as a 2903 light plate, and would apparently mount the same way too (it was broken when I got it, though.) Maybe it was actually meant for bells or something.
Here's one way a horn can be mounted on it.
The other method for installing it. Looks rather awkward this way. I can't picture any of these having been in the Fine Arts building or whatever.
My favorite alarm in my collection so far: a Simplex 2903-9001 light plate!
The back, which reveals it is the light version.
The tag info.
Both retrofit plates next to each other.
The light plate with a Simplex 2901-9833 on it (a.k.a. my Faraday 6020 horn.)
An alternate variation, where I popped the lens out of the light plate, then popped it back in the other way around!