Project Untitled

I have been working tearing apart the front suspension and the engine bay trying to get it cleaned up for paint. I really never liked the layout so I wanted to change a few things around. So out comes the air saw. Great tool for sheet metal work, especially older cars that have thick sheet metal. I did run into a few weird things and was would like clarity on.

Where my finger is pointing is a stress crack of some kind. Is this common and if so should/would there be other locations that are suspect?

Also in the second photo you will notice the inner fender well is crack. Just thought I would share.

I did drill out the ends so it would stop cracking. The K-frame was pretty rough, but that's another story.