Hello Howie
the lionel 18001 Rock Island 4-8-4 "Northern" came with brass gear but the boiler casting is rough. I had one of those back in 1987. It is a poor runner if you are aware of that but can be repaired. It has the same chassis as a old 736. I am not sure of the 18009 Mohawk as I never taken one apart.
Tiffany