As others have said, I suspect you're looking for pictures of something that doesn't exist. There aren't even windscreen demisting vents in newer cars, as it proved too much like hard work to route the vent pipes past the redesigned scuttle when the rollover protection hoop was brought in (probably around 20 years or so ago now, late 1990s?).
Have a browse through the pictures on the Dashboards thread
http://www.talkmorgan.com/ubbthreads.php/topics/140029/Traditional_Morgan_Dashboards (bearing in mind several of the older pics were lost when Photobucket blew up) - I suspect you'll find not a single dash-mounted air vent in any of them.
