Thanks everyone. I could not see any visible cracks & the engine has been running strong. I put some RTV silicone in that hole before screwing in the valve cover bolt....we'll see. No sign of antifreeze in the oil.

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"