National Auto Parts Company (Napco) has been out of business for a very long time. They did bolt on 4x4 conversions sold through GM and Ford dealers, and maybe Studebaker. This was before alot of offered 4x4s. I have seen a 67-72 Chevy C60 Napco 4x4 wrecker so not everything they did was pickup truck. This stuff is fairly uncommon to find laying around. They were like the old school monster garage of 4x4s. They typically modified available rear drive axles to steer axles. There were alot of different kits sold, all I really know about is the GM related parts, but I'll try my best to help. Post up some pics of the axle in question.