Any info on this Autocall Panel?

So a few years ago, My dad bought a $250 fire alarm panel for me on ebay. the listing was labeled as a “Simplex C-2000”. Even though on the panel, it said, Grinnell-Autocall C-2000. The model number on the CPU board though, was C-2224. This panel seemed like a rebrand of an FCI FC-2224, or Silent Knight SK-2224. I’ve looked up this panel countless times and only now am I finding one or two sources. It’s date code was 09/01/01. probably meaning that this was made on september 1st, 2001.

I’m posting this here in hopes that anyone reading this could provide me with some information on this panel.

Here are some pictures:
C-2224 mounted on a wooden demo board. On the right is a faraday 401140 trouble bell.

Inside of the panel.

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I do know of the manual, but lurker than that I have nothing https://buildings.honeywell.com/content/dam/hbtbt/en/documents/document-lists/silent-knight/archive/151051.pdf

I did find a PDF file linking to this panel, a 4 zone variant, and a 6 zone variant.
Here’s the file: https://firealarmresources.com/file/simplex-autocall-fire-alarm-system-c-2000-c-4000-and-c-6000e-33601-0/

Definitely a rebrand. My boss worked for Grinnell for a short period in the early 2000s, and they were rebranding Mircom FA-1000s as Grinnell M-1000s.