There are two galvanizing processes. One is hot dipped, and gives the mottled look. I doubt GM hot dipped them, just because of the added expense. Seriously, they were not anticipating us scrutinizing these finishes 50+ years later; and frankly didn't give a rat's a$$ whether they would last that long.
The other process is electroplating. Much cheaper. The finish looks more like silver paint. The downside is that they do not last nearly as long in a harsh environment. My brother chewed me out for bringing home some electroplate galvanized roofing nails. I had no idea.
Now I am wondering if GM used electroplate galvanizing. That would explain the pic in post #3 NOT having the distinctive pattern. I can assure you that the "virgin" (albeit a 54 year old virgin) shields that I have do NOT appear to have been hot dipped.
I will post pics when I get them off.
I cannot express how much I appreciate the pros, as well as the other very knowledgeable folks who post on topics like this.
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