Boy, I thought I could answer that. And, the more I thought about it, it's not that easy. I can tell the difference, but it is not easily described. A few clues: Stamped aluminum parts are soft, check an edge. Easily burned with hard buffing. Cast aluminum will have casting marks on back. Stainless is tough, and you can buff it easily (you can overheat it, and damage it, but not like aluminum.) It's rarely cast, will be stamped. Pot metal parts will be die cast, not stamped. And mostly chrome plated, but I'm sure there exceptions. Usually used for decorative emblems, ornaments, etc. Newer cars used anodized aluminum trim (thinking my '62 Chevy) and little, if any stainless. Emblems were chrome plated die cast pot metal.
