Those are Elizabeth hard trimmed and painted HZ's on their way to Dandenong for assembly. Not sure what you mean by late HQ with HJ body? All HQ's are HQ, HJ are HJ. The side gills were simply deleted mid 1974.

Side windows were always an option, it is just where they were fitted that differs. My guess is if you ordered them they'd be factory fitment, if they were ordered on a van already in stock they'd be aftermarket fitment. I've seen HQ build sheets with A09 on them, and as far as i'm aware dealer fitted options do not appear on on production broadcast sheets. Things like GMH supplied but dealer fitted towbars, mudflaps, radios etc.