 During World War II, NAPCO helped the war effort by producing specialized mechanical parts and assemblies that were tested in war conditions.As early as 1942 NAPCO began building four-wheel drive assemblies to be fitted to Ford, GMC, Chevrolet and Studebaker vehicles however NAPCO is primarily associated with GMC and Chevrolet pickups.From 1942 to 1956 4×4 GMC and Chevrolet trucks could be ordered by the government and civilians with a NAPCO Power-Pak kit and the kit could be installed later.