I have quite a few pairs of original tips. Some are the C7ZA-5C262 and C9ZA-5C262 shorties that Bob mentions. Some are C8ZA-5C262/C8ZA5C203 (KR and 68.5 CJ). And some are C9ZA-5C262/C9ZA-5C203 (428 Mustang/Mach). As far as I can tell none of them are chromed. I've cut many of the tips from the tailpipes and had them polished and none required chrome removal. Admittedly, I haven't seen every pair, but one would think that I'd have run across at least one pair that was chromed, and I haven't yet. When polished they obviously appear chrome...which I guess was the point when Ford made them. Also shown is a photo of an original tip I cut off a pipe, had polished, and rewelded to one of my tailpipes that is now on one of my cars. I've tried to weld the tips after they are chromed and the chrome always would flake off due to the heat of welding them. I would think Ford would have had the same issue if they were chromed. Stainless avoids that problem.
Scott