The welds he showed are definitely more toward the extreme end of what I’ve seen on factory stuff. But quite a lot of them are almost that bad. If all the factory welds on your car are good you’re definitely in the minority, typically they’re ugly at best. A-bodies seem worse too, I know my ‘72 Challenger and ‘71 Satellite both have better welds on average than my ‘71 Darts and ‘74 Duster did.
On the V8 K I installed on my Duster the welds on the steering box mount just broke straight through, when the steering wheel was turned the whole steering box would move left and right, opening and closing the cracks at the mount. Another spot that’s pretty notorious for breaking is the torsion bar anchors in the cross member. Even on cars with no rust at all the anchors have broken loose due to poor welds. The LCA pivot pin anchors are another spot that likes to fail. It’s definitely not every car, but it’s pretty common.
That’s exactly why I recommend seam welding, going over all the factory welds and reinforcing the K’s if you’ve got it out of the car. I do it on all of mine.
