Cracks on trans tunnel

While I was figuring out where to put a new fuse panel and rewire the whole car, I came across some cracks on the firewall at the trans tunnel. I probably wouldn't have even noticed if I wasn't looking for a place for the fuse box.

Has anyone ever seens this before? I'm wondering how, when, and why this happened? Do all II's have this problem? Maybe I'll never know. Guess I've got a little more welding to do...

Here's a pic of the stock fuse panel from my '75 too, if anyone wants it for reference.

I think I know what happened now. The cracks seem to line up with the bolt holes on the bell housing. My theory is the motor and trans mounts are so worn, the engine has been slamming into the firewall on hard launches through the years and produced the cracks. I also noticed that the radiator has some wear marks from the fan hitting it, probably during hard breaking, Which again seems to come from warn mounts. I've been real tough on it on more than a few occasions, so I think thats most likely the cause. And now I'm planning to put some real power into it...