Bulova 1973 Calendial

First, thanks to all involved for this fantastic resource!

Second, this looks like a Calendial D but a blue-grey dial variant (dial may be sun-faded). The "plunger' date quick change is a fantastic feature!

Third, Like neetstuf-4-u's, the inside of case back is ink stamped "3335" (https://mybulova.com/watches/1973-calendial-d-9028) with the same hour markers and "Automatic" within a white multi-line stripe.

Fourth, did Bulova change model names with different colour dials?

Fifth, would love to find an advert for this or any colour variations.

Sixth, what (if anything) does the small hallmark of "64" on the movement denote?

Finally, the (cheap and ugly) strap it arrived with will be replaced in short order.

Thanks and regards,

-G