I'm thinking it has to be in the head of block to head sealing surface area. The reason I think that is it only leaked when the radiator top tank was full, as soon as the top tank got to about half full the in the top tank, the leaking would stop. To me this indicates something high on the engine. When I pulled the valve cover there was no sign of antifreeze.
I'm totally open to suggestions on where to look. the front 4 cylinders (1-4) were dry when I pulled the head, 5 an 6 were wet which was prob from removing the head. I had the shop check the head surface for flatness, it had 1.5 thou warp not enough to cause a problem.