The numbers aren't in a line and there is a large gap between the model number and the year. They might not even be of the same font or size like I'm used to seeing. The question mark is there for a reason, because I don't look at 1968 Freemont Plant VIN tags everyday of the week and it may well be normal for that location and that year.
Looks like it does vary by plant...and this particular 1968 GS350 was an extremely early build date too. https://www.chevellestuff.net/1969/vin_samples.htm
Not only is it an early build, it’s the first year of the VIN being on the dash instead of the door jamb, so it was new to all the plants. Patrick