I have never found a definitive list of misc part colors. My opinion is:

-Master Cylinder - cast iron
-Brake booster - usually an anodized gold (although the factory may have also used a silver booster in some production because my original looked very silver.)
-Rear axle - plain steel
-Differential - cast iron with a plain steel cover.
-Spring leafs - someone else needs to respond. I think they are some charcoal shade.