Why would an intake be made 8 months before production of the 1969 motors and stamped for 1969 era but have 1968 build date? .
It wasn't. The 8 months was referencing the date spread between the casting date of the intake shown 8H (Aug 68) and when you reported the car was completed Mar 26 69. I stated an approximate span to be more specific it was 7 months and 10 days between the two dates you provided
It was late Aug 1968 when regular production started rolling at all three plants. "Pre-production 1969 vehicle's for special purposes were built slightly earlier. Engines, in preparation for the model release and the new "production year" were built before that date so the building of the 69 engines would have likely started in July some time or in some cases slightly before that for the few preproduction cars so they would be ready for the unveiling, brochure shots, and other advertising needs as well as all the crash, emission and other testing required for a new car.
They didn't start building or introducing the new model car at the beginning of the calendar year.
