I purchased the first set from a local GM dealer in the mid '80's, original boxes were marked as you see them in the following shots. I assume they are a month apart due to the dates (78D and E7). I have had these for a long time, paid $329.00 apiece for them if I remember correctly; the later dated quarters have had a mix of "0" prefix and non-"0" prefix tags. Most of the sheetmetal I bought as spares before they discontinued from GM, just because of that reason - plus, you could still buy fenders for $200 and change, quarters for $300 and change, cowl hoods for $400, dash pads for $80, etc., etc.
Started NOS parts purchasing from GM around '80 - veteran pack rat. Worst mistake I ever made was buying for one car, up until the point they multiplied on me. By then, it was too late for a lot of NOS stuff from GM.