The momentum of four wheel drive popularity definitely began after World War II. The need for this off-road extra during the war forced 4×4 technology to develop at a fast pace. Thus, during the early 1950’s, several independent companies began to appear offering a four wheel drive kit for light duty trucks.
Major pickup manufacturers were not yet offering this as one of their factory options so a great opportunity existed for new companies. Kits from emerging companies such as Marmon Harrington, NAPCO, American Coleman, and Fabco were designed to fit specific makes of trucks. For those that traded their vehicles regularly, these kits could be removed and installed under a newer truck. This was a big selling point as the finished product plus labor usually retailed for almost as much as a new light truck.
It didn’t take long for General Motors and other major light truck producers to realize a 4×4 option should be made available to their new vehicle buyers. Why should their franchised GMC and Chevrolet dealers be taking new unsold pickups to nearby independent installers to add the 4×4 option?
General Motors solved this problem and with less investment capital! Rather than engineer a totally new system (4×4 were not big sellers nationwide), GM installed an assembly line unit that was already being used. The Northwest Auto Parts Co. of Minneapolis, MN (NAPCO) was contracted to provide kits to one of GM’s truck assembly plants. As NAPCO was already the main installer of 4×4 systems under GM vehicles, this marriage was a natural.
NAPCO would continue to have their franchised installers in most major cities, however GM would offer the same system from their assembly plant. Of course, when GM used the system in 1957-59, they left off the chrome NAPCO trim fender plates and did not refer to the word NAPCO in their shop manual. The large letters NAPCO were always cast in the front axle housing in view to a person looking under the front bumper.
The following pictures are from an original 1957 Chevrolet 4×4 brochure. Note the emphasis on rugged use.