[Ron61]

The C6AEXXX tells you that it is a 1966 block and the A will tell you what car it is out of. The E is a Ford Engine and the rest are running changes made during the production year. Mostly minor stuff. But from what you say about the freeze plugs and mains, I agree with Ernie. It sounds as if you have a real 427. The 352 was cast into ever Ford block from the 332 through the 428 Cobras.

Ron