It should be on the back of the petals/spokes.
If you do a quick search in the classifieds section, I bet you can find some postings that show the stamps as people always want to know that info and that the wheels for sale are real etc.
If you still can't find a shot, I can take pics of mine tonight since they are off the car at the moment.
EDIT - Check this one out:
early fuchs for sale
it shows an example on an early Fuch.....
-Chris