What kind of metal on pilot wheel frame?

The metal frame that the 2 front axles are in on newer Lionel steamers is shiny. Is there a plating on them or what?

The newest I can go is my son’s DC 8903 2-4-2. It is shiny. I would guess that it is zinc plated. The picture was difficult. Shiny is hard to photograph. I observed some some discoloration in the stamped lettering.It didn’t come out in the picture. The draw bar shows some corrosion specs. The rust isn’t uniform indicating a bleeding through. Just a guess.

My newst Lionel steamer has a detailed die-cast pilot truck. What kind of steam engine are we talking here?

Jon [8D]

Lionel starter set 4-4-2s.