Great post! I recognize many of these cars from my early adulthood. The panel truck was used as a "rolling store" in my part of the country at that time. It was loaded with candies, fruits, snacks, cold drinks, etc. and would travel through the big acreages, where farm labor was busy at work, blowing the horn for miles. The laborers would get all excited and announce that the rolling store was approaching. They hovered around the truck selecting their items and visiting for a while. It was definitely a high point in their day!