Engine color for 1935 ford

[vetpenny]

I have seen 1935 engines with silver color and light green. Most of the 1935 engines I have seen are light green but a few are silver color. People who have silver engines claim that some of the manifolds are aluminum. My manifold is cast iron therefore, I choose the light green color. Are both acceptable or does it depend on the manifold type? Thank you for your help.