Ever since the release of the first pickup trucks, aftermarket companies and custom shops have been looking for ways to make them more rugged for off-road driving. Shortly after WWII, a company called NAPCO began offering 4x4 conversion kits for civilian trucks from Dodge, Ford, and GM. Soon, GM started offering these kits as factory-installed RPO options, and then developed its own 4x4 system to meet demand. A few decades later, trucks like this K5 Blazer were built with off-roading in mind, and buyers upped the ante even further by modifying them with lift kits and bigger tires.