Aside from Glenair, few sources exist for backshells for HD-104 connectors, which are the rarely used "size 6" D-sub body, slightly bigger in all dimensions than the DD-50 or "size 5".
Strangely, the faeries put a size 6 backshell in one of my desk drawers, I don't know where it came from, and still haven't figured out how to buy them in the U.S.
They are made by a company called Inotec out of Germany. Their website in english: http://www.inotec-electronics.com/cms/servlet/Query?node=108422&language=2
Their german website translated by google: http://translate.google.com/translate?hl=en&sl=de&u=http://www.inotec-electronics.com/
Their catalog: http://www.inotec-electronics.com/cms/files/1/22286618732500.pdf
Search the catalog for part number DG104MSX.
