The Apple Disk ][ drive is a Shugart mechanism, it's based on the SA390 design (an SA 400 floppy mechanism without the controller board), which was made specifically for Apple, as they wanted the least expensive 5.25 drive they could get. Here's the full story:

http://apple2history.org/history/ah05/

There is an early Mac prototype (in a plexiglas case) that used a disk ][ for storage, here's a picture (supposed to be from the second run of Mac prototypes built, serial number 15, in the Computer History Museum's collection):

http://www.bitsavers.org/pdf/apple/mac/pictures/Mac_Proto_Case_%2315.jpg