In an earlier "Dave and Ryan" video, Dave Olson mentioned that the Legacy Berkshire had Mars light that would light/fade/light/fade in a simulation of an oscillating light. The 2018 and 2020 catalogues show that only the American Railroads #759 has the Mars light, but the Nickel Plate #765 did have such a light for a good portion of its life. The restored version today no longer has the light.
The prototype 765 currently does have it's Mars light. As I recall, it was reinstalled in 2016.
Here she is on the Joliet Rocket in 2018: