Where I live the guys find an old rust bucket with a title and do a complete frame swap using whatever is commonly available from the local junk yard (salvage yard). Early 70's to late 80's Chevy or GMC. The wheels stick out past the fenders but appearance is secondary. The diesel guys also like a frame swap but use big truck fenders to cover the giant tires. On the weekends in the dry summer months they compete with each other running through the mud of a local lake bottom. It's all for fun. This type of modification I would consider as the #1 budget option.
After the first half of 1955, the truck frames and axles became wider so your are limited on 4X4 used parts that fit inside the fenders of an AD truck. Doing 4X4 on an AD that is in good condition, other than NAPCO, needs careful consideration towards resale value i.e. you don't want to drop a lot of $$$ into a truck that may not sell well in your area because of personal tastes in the truck appearance. If I was doing a 4X4, I would try to clone what NAPCO provided many years ago.
The stock truck 235 engine, 4 speed transmission and rear axle combo were designed for use in real work trucks. Out in the field on a farm or with the US Forestry Service (still used today) running over rugged mountain roads. Low speed and high torque. They were not designed for cruising the expressway running at 75 mph.
