Ok different way of saying it same end result. The one thing that seams to be fact is that the sound is coming from the block section of the engine. How else can you explain Ford changing out the blocks, meaning complete short blocks and the sound going away? My quest and I wish there was Ford tech that could shine some light on this. Is where in the short block are the failures happening. A rod knock is consistent, and as we all know, and a cylinder load test should show if its a rod or not. But a main knock will not change pitch nor dissipate with a cylinder load check it remains constant regardless. I don't like throwing parts at something just to see if it goes away. I believe this needs to be handle with some intelligence. Boy I maybe short in that department!!!!