Magnum cylinder head crack

Yeah, I'd say it's a crack from someone putting a bolt in that hole and tightening the hell out of it or maybe over tightening the stud. If that hole is open to coolant, time for another head.
This engine is new to me in a truck that I just purchased and drove home over 200 miles. No signs of smoking or coolant in oil. I started pulling it apart because the RH side manifold had a exhaust leak. Someone has been there before, the manifold is a Dorman replacement and the bolts were not OEM.