My GT has a even lower VIN #: 941671024, and the gauges says 10/68. I wrote to Opel in Germany about it, and they say it is a 1969 model year. It was shipped 19 December 1968, and the production date is always very close to that. So I would say your GT is produced early in 1969.
You can read the answer I got from Opel in my post here:
http://www.opelgt.com/forums/general...tml#post117313