Thanks, Jon. These are great! You were correct–I didn’t have the wiring schematic when I tore into mine.
With regard to your question about which speaker, I’m doing an LGB mogul right now with one of these in the smokebox. Don’t laugh, but the steam dome off of a Bachmann Big Hauler makes a fantastic enclosure for it! It’s a 4-ohm speaker, so I’m pairing it in series with another 4-ohm speaker in the tender. I had a 2.5" Visaton speaker in there at first, but the Visaton drowned out the smokebox speaker. I switched to a 1 3/4" 4-ohm speaker that was in the tender from its original owner, built an enclosure from a plastic baby food container, and the combination of those two speakers sounds fantastic. I’ve got a Tsunami2 decoder in this loco, so I was able to adjust the EQ to really get the most (to my ears) out of these.
The TCS decoder I’ll be putting in my C-19 has two speaker outputs, so I’ll likely go with the 2" Visaton speakers I’ve used in some other projects. I’ll probably do the same thing as with the mogul–one speaker in the boiler, one in the tender.