Welding body seams

Now.. If you use the flanging tool , lap joint AND you want to do the job once. I suggest leading the welded area then applying filler over that. Leading as it's called, is pretty similar to sweat soldering a copper pipe. When you lead the seam it will wick behind the flange basically eliminating corrosion in the joint. All the metal you welding is clean and there no other way I know of getting better rust protection.Then apply seam sealer inside and filler outside. And for gosh sakes dont use Bondo (it shrinks over time, creating cracks) Use a Quality filler like Evercoat Rage. The lead and filler can be found at www.eastwood.com . That's where I got my materials. It's not exactly cheap but it's the best way I have found to make a lasting repair. I didnt use lead on my 1/4's but thinking I should have. I used lead on the a-pillar/cowl repair area. Everywhere else, I sprayed with self etch primer, then a high build primer. Epoxy Primer over the fill n sand will seal out just about any moisture, though expensive @ about $50 a Quart. I just keep my sheetmetal indoors and air conditioned with the zinc primer it works. I have the luxury of keepin parts indoors with no wife..lol I hope this will help a few.. Ask.., I'm not a pro but sure there's more input to this post.