They don't look like molds. Look at those fender panels: they are smooth & if you put cloth & glass on them - the inside of the new fender would look great - and the outer rough. They are the opposite - they should be the negative. Unless you used them to make mold & then make parts. That is really labor intensive for a GM dealer to undertake. I'm a skeptic. Show me the GM part numbers.
In the early 1970's I had identical looking 63-64 front fender louver panels bonded to one of my cars & got them from Russell Chevy, Fairfield, CT. Now they came from GM, but the dealer may have bought them from one of the aftermarket fiberglass vendors at that time (Don Bailey Vette Shop; Ecklers, Motion).
Hand laid - they were the only panels available for those parts. Aftermarket match molded fiberglass had not yet been introduced. They were OK on the outside, but the inside was rough & bumpy. Years later I replaced them with smooth press molded & put them up for sale. Remarkably the left sold & l still have the right.