Yes, the year was figured out and posted when he put up the correct vin. You will even find the exact day it was assembled in another post and it wasn't in December.
Did you read the thread? The casting date was also posted earlier.
If you didn't know, you quoted Frank that owns the GTS Registry so i'm very sure he knows what he's talking about!!!!
Yes the motor was assembled on 10/29/68, so it is very likely the Scheduled Production Date(SPD) of the car it went into was the first week of December. Generally dated parts/assemblies can be 3 months prior to the SPD of the car.