Knowing what we know about Ford engine date codes, a matching numbers 390 engine block to a car built on 11/10/66 would be a 6J or a 6K block. Even better would be a set of heads with 6J or 6K and a month date maybe a little before block date. Ie; 6K18 block with a matched set of heads dated 6K11. BUT... my question is..would there ever be a chance the head date code would perfectly MATCH the block date code? I feel the separate production of these components in a factory/plant would make this impossible..