Upsman, I just went through what you are going through. A while back I took the tank out of my 49 and steamed it out good. It looked realy good inside. I put it back in the truck, and a little while later, I started seeing rust in the fuel pump bowl. I bought a new tank from "Chevy Duty" and when I got it installed, I put gas in it, and it leaked like a sive around the hole where the shut off valve threads into the bottom. The new tank has some design flaws in it. It isn't near as good as the original. I took it back to them, and got my money back. Then, since my original tank wasn't really in too bad a shape other than the rust, I bought a cleaner/sealer kit from Eastwood, and did the job myself. The tank is sealed, and back in my truck and working great. I had asked a local radiator shop here about boiling out the original tank, and they told me that their insurance people made them stop messing with gas tanks because of the danger factor.
