I couldn't find the exact one, only one that had the same pin layout. However the pin sizes might be different. After scouring a ton of 30 pin connectors the only one that seems to match is by
Amphenol FCI. Part number is 52057-102LF (at
mouser). FCI has a whole 'Metral' series of backplane connectors, however these are much newer than the HDI-30 so I'm not sure it would even fit.
Keywords to look for are "5 row" and "6 pos", as those denote the pin layouts of various connectors.
Further research opportunities:
* Email various
connector companies (see also
their HDI-30 page) as well as
TE connectivity
* Try to find Apple's HDI-20 floppy connector manufacturer, as its probably the same (its 4 row 5 pos). Alternately the HDI-45 video connector
* "Square DIN" might get you somewhere but I didn't find anything with it in a quick search. Also, HDI-30 is slightly rectangular.
* Find out what the name of the metal cage(?) surrounding the pins is, that might narrow search (it can't just be 'plug' can it?)
* This is likely a legacy connector not used anymore so that might need to be included.
This was an interesting read on Amiga's weird square power connector.