Here's a picture of the weld on the knuckle of my Dana 25 axle, which (AFAIK) dates from c1949.  I had sandblasted the axle housing, but the morning dew got to it leaving the rust pattern you see (which was easily cleaned off). 

It's the circumferential weld that really intrigues me.  The other welds (the one holding the brake hose holder in the picture, and the ones on the spring mounts, not in the picture) are clearly done by hand.  But this one weld is not--it's a much higher quality.  Since they didn't have robotic welders in 1949, how did they do this?

This is just curiosity--I have no inclination to try to do anything like this myself!

-Paul