This, the very first N scale brass cab-forward, was manufactured by Nakamura and imported by Key. It came in both painted and unpainted versions (the only number on the painted versions was 4294). The painted versions were available either as all-black or with a silver/gray smoke-box and lower cab-front.
This AC-12 was the only cab-forward made by Nakamura. All subsequent runs of Key cab-forwards were manufactured by Samhongsa (starting in 1986). I'm told that this Nakamura model beats all of the subsequent Samhongsa releases, both in detailing and performance. It also tends to sell for several hundred dollars more than the Samhongsa cab-forwards.
For a 1984 release, this is an excellent piece of modeling. Paint and detailing are quite stunning, and performance is similarly impressive. Mine runs as smoothly and as quietly as any steam locomotive you'd care to name (Kato's legendary Mikado included). The pickup scheme is a bit odd, but I can't argue with the results. The forward-right drivers pick up one rail and the rear-left set of drivers pick up the other. All the rest of the wheels are electrically neutral. Nevertheless, given the span of all those big drivers, I've had no problems with stalls. Mine also stays on the rails quite reliably - no problems with narrow radius curves and no flakey derailments. There are no traction tires, but then again, it doesn't really need them. This baby will pull a ton and then some.
The top-end speed is very reasonable. And although slow speed creep isn't bad, the smallish coreless can motor (Namiki/Japan) can't quite match the crawl speeds of more modern steamers. That's a minor quibble though - overall performance is stellar.
The locomotive comes with a small dummy knuckle coupler on the pilot. I'm not sure if the tenders were delivered with couplers or not, but the one I have has a Micro-Trains coupler assembly screwed into the provided hole in the tender. Also included are some "ala carte" parts (to be installed by the modeler) - six pieces of window glazing, brakeshoes, numberboards for the cab, and lenses for the headlight and tender lights. The model does not actually come with any sort of lighting (cab or tender).
To pull the shell, remove the screw inside the dome on top of the locomotive shell and the screw on the bottom of the chassis up by the pilot. It will lift right off at the point.