Slant 6 Block Crack

That's a stress point where the stud screws in. Could be it was removed for some reason and when it was screwed back in there was some trash in the hole and it cause the crack. Could be some dumbass cross threaded the stud. Who knows why it cracked? Cast iron is some great stuff, but that's one of its downfalls. It can crack just sittin there. As many slant blocks are out there, I don't think I'd take a chance. All it could do is leak oil....but like cast iron, unless you find the ends and stop the crack, it will keep cracking. Then the question comes into play, Is it worth fixing, or do you find another block? I say fins another block.