I know I have seen that cross too leon, these machines turn up now and then here on QB and VS, it's the same every time before we manage to track down models and makers. There should be at least a couple of threads on it here.
I think the part is original Nmaree, it's not entirely uncomon to have one piece more or less untouched by grime and rust. If you are lucky, the brownish discoloration turns out to be oil and grime. It darkens like that with age and it me it looks exactly like that, and probably why the one part has stayed clean longer.