Your hypothesis could be correct, and that would be a great story!

Another statistic that I wondered about is that the distance between the VIN numbers (138444 and 116567) is about 120,000 units, which could be the number of vehicles GM built between late October 1967 and January 1968, assuming the VIN number were sequential throughout all GM plants. Is it possible that the VIN numbers on my car were changed at the factory, and that may be one of the reasons the car was originally green and then painted blue? This may be a stretch, but I am trying my best to understand what happened. I did reach out to PHS, and he is fairly insistent that the VIN was changed, though where and when wasn't specified.