Did that to my '94 6BT Dodge. "Staking" is a common practice in the machining industry, so it is effective and cost effective. The company I work for does that on nearly all of our assemblies. Never had one fail yet.There is a method called "staking". Use a punch or chisel and hit the edge of the hole so the dowel pin cannot come out of the hole. The hole should be deformed so-to-speak.
That agrees with what I'm trying to say. The 'slot' should not have broken through the dowel pin hole, but it did. Staking 'should' work, and it's an approved method in a lot of machine assemblies. But just like that broken part in the casting causing that slot, it's just not 100% dependable! The timing cover bolts 'should' remain tight, but they don't!The "slot" in the dowel pin boss was already there. Broke through when the dowel hole was drilled. That portion of the casting is rather thin.