Bakerallen, I have the flange tool that you are speaking about, one side flanges the panel and the other side punched the holes so you can tack the panel in place. It is recommended that you completely weld up both sides of the lapjoint or a possible rust problem will develope. Some times you can not get at both sides so you maybe only able to weld one side. If possible seam seal the other side to prevent moisture from getting inside the joint. Remember those Japanese trucks from the 80's where the beds rusted in half on a horizontal line running down the entire bed side? This was due to the two piece bed side s being lapjointed and only spotwelded. Had they welded both sides completly the beds would have lasted a lot longer.
