I have a Radio Shack 5 1/4 external FDD (mod. 25-1060
) which I believe
was only useable on some of the 1000 models. Certainly not on my 1000SX
in any case. It has a 26+4 card-edge connector. Radio Shack seemed to
have some unique(non-standard) ideas for their cabling. 
        Even their internal floppy drives deviated from whatever
connections most others were following at the time.  The drive you're
referring to above is the external 5-1/4" drive intended for use with
the 1000EX and 1000HX systems.  There was also a similar drive with a
DD 3-1/2" mech for these two systems.  On my 1000HX I used to put my
BBS online for testing using only the internal 720k drive and the
external 360k drive.  It was a handy way to give people a means of
transferring private files directly too me too.  I believe the
external 720k drive was p/n 25-1061.  I didn't aquire one of those
until years later.
        Jeff
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