AAR is correct. Longer in solution the more the bright finish darkens. Alodine 1201 will turn the color more like a holley body. If you look at those alternators the texture has been polished and the originals were not polished just removed from the castings and machined an assembled.

Early on everyone seem to think Disc cars had yellow zinc MC covers because that is how a over the counter part looked. But they were painted black from the factory for assembly line cars.