[70post]

I don't think GM did any of it....meaning my bet is that the roll steel sourced for the dust shields was specified to be galvanized (at the mill,etc). Then the pieces got stamped out from the rolled sheet steel.

Galvanizing served a sort of dual purpose...protected the metal pieces that were stamped out from the rolled sheet AND lessened the wear and tear on the stamping tooling (since zinc is a soft metal). Same thing on alternator fan blades and many other parts.

Just my "speculation" on this.....gas tanks are the same thing/process (albeit a different coating/plating)....at least when it comes to the GM Abody cars of the era.

I'll try to get a pic or two of one of the galvanized dust shields I referred to above.