A pic of the Fuji Robin EY25D engined HD-8 from a newspaper ad:
From
THIS past ODK thread.
As is evident from the front axle mount, this was the second series [yellow] HD-8, not the first red series. I can only recall encountering one Robin engined HD-8, and that was a yellow one, back in the 1970's when my family had a Greenfield agency.
Dunno quite what the story on the bonnet louvres was; they seem to be found on the Red series HD-8's, but not all of them.