AGmajor@gmail.com wrote:
> I hve seen two different types of connectors for Apple II drives.  One
> is a 19-pin D style, and the other has a small blue rectangular plug on
> the end of a ribbon cable.  Is there any difference between these
> drives (besides the connector)?  Is there a way to convert one cable to
> the other?

Depends on the drive attached.  If it is a singular Unidisk 5.25" drive, 
then no, there is no difference and yes you can convert one to the other 
with an adapter that is fairly scarce by this time.  (But available via 
at least one link  provided below.)

Look for a Disk II to IIc adapter, it will allow you plug in the 20 pin 
header connector to a DB19.  Picture link below.  Most of the ones I've 
seen to not have the long cable, the two plugs are back to back and have 
no real 'length'.
http://www.connectworld.net/cgi-bin/iec/fullpic?2iQBXEbF;L1564;6

Going the other way, plugging a Unidisk into an older Disk II controller 
    will also work, but I've never seen the reverse adapter.  But here 
is a picture of one anyway:
http://www.connectworld.net/cgi-bin/iec/fullpic?2iQBXEbF;L1561;23

Thankx,
Ed

Additional resources:
http://apple2.org.za/gswv/USA2WUG/TIGER.LEARNING.COMPUTER/Making.Disk.II.adapter.cable.tx
http://www.connectworld.net/cgi-bin/iec/02fplL14.html