In the late ’40s and early ’50’s the name NAPCO really stood for something in the automotive world. But there is a good chance you have never heard of them before. If you had a four wheel drive truck back in those days it was most likely designed by NAPCO (Northwest Auto Parts Company). Founded in 1918 as a specialized mechanical parts shop in Minneapolis, Minnesota. Which if you have spent a winter in that part of the country you immediately understand how a shop like that could end up specializing in four wheel drive systems.
Exact dates on when NAPCO started furnishing 4×4 systems to Chevrolet, GMC, Studebaker, and Ford are not known but many believe it was as early as 1942. NAPCO’s main business was Chevrolet and GMC by far. Interestingly up until 1956 if you wanted a 4×4 you would go to the dealer and buy the truck in two wheel drive form then NAPCO would ship you a crate that had the 4×4 kit in it weighing as much as 1,400lbs. Apparently it was fairly easy to install, only required drilling four holes and then you had fully converted off-road beast, or as they called it in those days a “mountain goat”.
More information available here.