Honestly I built mine through research, and my own ideas. Don't cop out, and buy plans. It is simple make your fire box at least 30% the volume or your main chamber. Reverse flow, and enough intake, and exhaust to let the fire breath. Good luck man.
Trucks are a little more complex than smokers. A book would help a do-it-yourselfer.
Smokers are easier to build if you have a plan to follow. We sketched our smoker plans out so everything would fit the first time. I have seen some builders that have made mistakes and had to redo parts of their build because they didn't think it all the way through.