I have an 04A build 68 Z/28 and my bolt ons are dated 1 wk of April. Starter 8D5, alternator 8D3, exzhaust manifolds D18 etc.
Manifolds cast April 18?
Stovebolt- Your question concerning "component assembly date falls before the engine assembly date", yes it happened. There are many, many examples of this. There was variation in this area from one car to another and the reason there is no "set" rule. Believe some of this had to do with model (specific part for a model like our 01B 68 Z/28 has a Aug07 alternator), and no FIFO (first in-first out).