If they look like the washers in the auction photo, they are very unlikely to be fake. The markings were dropped with the intro of the script logo calipers c. 1985. It could have been that the patent ran out, so the stamped declaration was no longer needed; it could have been to save pro duction costs... maybe both. As far as I know there are no other brands with exactly the same shape.
Tom Dalton
Bethlehem, PA, USA