I have never done it, but I would think a long bed could be made out of 2 either 3/4 tons or a long bed and a short bed. The splice could be made at the post. If you do the weld on the post side, the weld would be covered by the post and then the post plug welded on. I have set in some pieces of the tubing. I was not making a show truck, but it takes a sharp eye to see the splice. An experienced body man could completely hide the weld. One of them I filled with lead just to see if I could still do it and it turned out really nice.