Something really hard hit that really hard to enable a chunk to be blown off. It is best to address this before it puts any unnecessary stress on the rest of the steering linkages. As far as welds, factory welds on the K's were scrappy at best.
I boxed it in and gusset it out to make sure things stay where they need to be.Who knows what caused it. Clean it out, vee the crack, weld it all up and box it in.