Ford used a simple casting code to date certain cast parts.
The heads will have a 4-digit date code under the valve covers, and the block will have a part number and date code cast in the starter area.
Ford Date Decoding id
Ford and Mustang Intake manifold. 4V, 2x4v, 3x2v, Ford Mustang Mercury Tunderbird Galaxie Torino Fairlane Cougar Eliminator Boss Cobra Jet Tunderbolt and Shelby.
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The heads will have a 4-digit date code under the valve covers, and the block will have a part number and date code cast in the starter area.