Thanks all. Mine are missing. Scott, my car had both quarters replaced and one side does have a GM part number sticker on it.
When I stated factory tin I was referring to the sheetmetal the factory installed. I see how my post could be taken in different ways. When originally assembled, there were no labels on your car's sheetmetal. Hopefully anyone who had a quarter replaced years go did not receive a collision cut. They slice the quarter's sailpanel under the original sail panel/roof skin seam to save time.