This hole was due to corrosion. I prepped the surface with a well worn flap wheel, red scotchbrite, emery cloth, and lint free paper shop towels. I cleaned it using acetone based brake clean (CRC green can), and straight acetone (Dupli-Color brand) to ensure the area was free of any and all debris, grease, corrosion, etc. Repaired it using standard JB Weld, and it never leaked a drop after that. I saved myself a few days of work and a few thousand dollars in parts by doing this. The hole was actually in the head. I would have had to pull everything including the head to replace it due to this one tiny pin hole.

I traded the vehicle in for an Excursion.