According to Jerry M's book...
3932386 May 1968-December 1968
3956618 December 1968-April 1969
3970010 April 1969-September 1969
3932388 December 1968-September 1969. Fairly rare casting. The casting date is located next to the casting number, behind the LEFT cylinder head.
It appears that several of you know this to be a fake trim tag. Is it the 'fatter' text/characters that gives it away? I guess I'm not very good at identifying these tags. I keep comparing it to photos in Jerry M's book and the characters appear to be the only difference I can detect with my failing vision.
Rich