As I understand the Williams brass locomotives were all new tooling at the time. Korean factories can fabricate everything very efficiently out of brass and they do it very well whether it is all brass construction or the various castings required. However, someone can correct me, I believe that some of the early Weaver brass locomotives are the same tooling as the Williams versions.
The Sunset model I posted is off a little. It is the High Iron series from 2004. The front porch is too long and the pony truck slightly longer to accommodate 3R flanges. However with the correct 36" wheels on the front, it is not quite as noticeable. The Precision Scale is one of the nicest ones I've seen. At $1k used, another $300 for a better working drive, and having to paint it that is out of my reach for some time.
Detail of the Sunset lead truck.
Regardless, the Williams model still looks pretty good coming around the curve.
Well shoot ... was thinking of thinning the herd, but I really like my Williams one too. :-)