[Sirrotica]

Believe it or not, that was likely how the car came from the factory. The frames were manually welded, and the welds looked like chicken scratch when new. Fresh thick undercoating will hide a bunch of defects, especially if the person looking at the car doesn't scape the undercoating off to see what it's hiding. Having owned a state inspection garage in PA I've seen about every trick in the book to hide bad frames that were rusted, or cracked. Fresh undercoat is usually a dead giveaway to get a pick hammer and start probing the frame. You should see the faces of owners when you find what they thought they had hidden with tar, bondo, duct tape, etc....LOL

That seam is 2 pieces of channel overlapped and joined by welding. These poor welds are the reason when pressing one of the cars into dirt track service you would go over the whole frame and likely use 10-15 lbs. of welding rod re doing the factory welds.

Over the years in the mechanic business, I have had to repair frames on street driven cars that had failed welds numerous times. There was little if any QC on the frames of early cars. Many times it looked as if they hired someone off the streets that hadn't ever welded before, and stuck them on frame welding as it was a dirty, and hot job. Being on piece work as well as having to turn out so many frames in an 8 hour shift, doesn't promote quality assemblies.

Most people that are learning to weld have a tendency to go over the seams too fast, not melting the base metals enough, and not using enough filler rod to make a strong weld. Good example in the picture.

In 50 plus years of looking at the bottom of cars, I've seen plenty of shoddy welds from the factories. GM was probably the worst for bad welds. There's a reason that manufacturers went to robotic welders, over human welders, every weld is a duplicate. They also can keep up with someone speeding up the line, while keeping the quality adequate.