[SS Tim]

Pick up beds were an evolution as previously mentioned. If you look at the intended users it makes sense. Smooth sides and a rectangular shape were easy to load, calculate load weight, easy to access and empty. The steps were a natural extension of the running boards and useful. Later as the trucks became more widely used, people began looking for creature comforts and styling. Dodge grafted on car quarter panels and GM put huge fiberglass fenders on the looked like a smooth side. Non-commercial users liked and demanded more, so the add on fixes became integral components and the fleetside style bed we know became a regular production vehicle. The wood floor carried on as did stepside style because there was still a market for them. Be it government or industrial "low bidder" or the rancher/ ag user that still demanded a grain tight bed to keep loose loads and wood floors for livestock. Soon most of the non-commercial trucks were fleetsides, then the mid '70s 4x4 and truck craze happened. Now people wanting something different decided that the stepside offered a different look and better access to their coolers. Again soon the look went away and due to low productin numbers then they were gone from production. But every once in a while someone in marketing tries to do it again like the mid '90s beds which were now narrow widebeds with fenders stuck on the outside to provide steps and a marketing edge.