In among my various hauls comes all kinds of parts I put aside to identify later - and this is one of them.
It's a 3.5" floppy drive, with "ASCO November 1984" printed on a label on the side. It's taller than a 5.25" CDROm all up, but only about as wide as a normal 3.5" floppy unit from a more modern Apple. It looks similar (but not identical) to some other Lisa2 3.5" floppy drives I've seen in photos online, mostly differing in the aluminium cover - the rest looks pretty similar.
It seems completely seized up unfortunately - unless it needs power applied to allow any of it to run, it won't take a floppy more than about 2/3 in before hitting that bar that should open the slider, which doesn't budge.
http://www.danamania.com/temp/oddfloppy.jpg has a few pictures of it. I could take more photos from other angles if it's needed for a positive ID.