[tom406]

The part numbering system is most indicative of when the part was engineered and began being produced. Like Speedrx says, some parts (if they were not changed) carried on for several years. But if there was a design change then the part number changed, just like every other company.

Occasionally these parts even preceded the model year. An example is the C3AE coded 406 block in my friends late production 1962 Galaxie. The actual casting date is from 1962 and precedes the build date of the car. The block design was apparently earmarked for 1963 production, but got "let out" early.

But most unique body and special hipo engine parts changed year to year, especially during the late '60's early '70's, so the part numbers are an excellent indicator for helping to determine application or originality.