They aren't actually on the quarter panels, they're on the "mud guards" which are plastic. It's just 3M clear paint protection film. You can buy it at most paint shops or on ebay and cut it yourself. To take it off you'll have to use a heat gun and razor blade and very carefully scrape it off. Then use adhesive remover to get the glue off. I don't think you'll be able to do it without hurting the paint if the film is that old and cracked up, it will be stubborn to remove, so plan on having those two guards repainted before you put the new film on.
Oh and you can try plastic razor blades first, they might save the paint.
