The best way is to butt weld them if at all possible. No moisture will ever get into the "seam". There is no seam. It's all one beautiful solid piece again!(almost) Use "twenty gauge" brand wire with gas. Always use gas. And butt means Butt Tight, no gap is necessary. Sometimes there is some due to not-so-good matching. Use flattened copper tubing in the back because you will blow thru until you get real good. the weld will not stick to copper, so it "fills". If you don't go slow and jump around and wait for some cooling, then you WILL warp it and be in deep do do. The final weld look (before grind)is overlaping spots. See my tech tip on fix a crack. If you don't grind slow and jump around you WILL warp it and be in deep do do again! Then epoxy prime, A small amount of "glass fibered" filler, then regular good quality filler and so on and you will never have a re-rust.
