When you depart from the body and interior parts that are usually very specific to a Mustang, and go under the hood to parts used across multiple lines, you will find less and less C7Z part numbers. Core engine parts, windshield washer bags, heater hose, belts, etc. tend to be C7A or C7O (for parts new to 1967) or back to C2 or B8 for example. Ignition point sets are B8Q-12171-A. A 200 I-6 distributor weight spring is A8TZ-12191-A. That's correct - a 1948 part number! The quarter panel courtesy light bulb is a B6AZ-13446-A part.
It makes a lot of sense to continue to use parts that have already been designed, tooled, proven, warehoused, etc.
The FDA-14303-A part is a bit odd due to the three character prefix, instead of the four character variety that we are used to.
I looked for other FDA parts, and came up with only two additional. FDA-18471-A is heater hose. FDA-18583-A is the Mustang heater blower motor mounting gasket.
