In your post I see two different cards. I see a Disk ][ Card and an Apple 5.25 Drive Controller Card.
Yes, I was demonstrating the difference between the DB19 and the 20-pin headers on them. It's actually the same electronics on those cards... only the connectors (and number of connectors present) are different.
So basically, this drive can be used in current form on a 5.25 Drive Controller Card and with that dongle it can be used on a Disk ][ Card? (Whereas even with that dongle a Unidisk 5.25 / Apple 5.25 Drive would not work on a Disk][ Card?)
I'm sure there are/were adapters that went both ways for various reasons. They're all compatible, with various restrictions mostly having to do with daisy-chaining. You can daisy-chain two Disk II drives on an Apple 5.25 Drive Controller Card (there was only one connector on there...) but you have to hook up drives one-for-one on the Disk II card. And of course only the A9M0104 and A9M0107 drives had the daisy chain connectors on the back to begin with.
