[Mark IV]

Well for one, not all 1966 Ford blocks were stamped with a VIN. HI-POs and 427s were, most were not. The casting number and date code indicate a 1966 block.

When Ford VIN'ed a block, it was stamped on the flat area behind the intake manifold at the rear of the block. Common sense would indicate that a "stamping" is a recessed marking and NOT a raised, cast number on the block. But, hey these are gummint people!