Poster says he, himself, painted a 69 Camaro. Says it took a gal. Says the 1949 short bed, he has right in front of him, is a considerably larger area. He has painted at least two vehicles with some brand, and knows the coverage of whatever color family he used. Seems as though he is the better judge than any of our guesses or a paint store's guess. No one can pin it down to no. of quarts. It's a non answerable question. Everybody who does DIY painting buys too much or too little.