Joe, I've been patiently waiting to see pics of that truck. Thanks. I only know of about 4 trucks total that were converted by NAPCO in the 1967-72 era, but there is no telling how many are still hard at work on a farm or ranch somewhere.
For more details on my blue 1971 1-ton NAPCO check it out. Enjoy the pics.
http://www.ccountry.net/~tmobrien/trucks/napco/71napco/