Floppy drive support is as follows:

Mac 128K, 512K, 512Ke, Plus, SE/30, Classic, Classic II: Can accommodate one internal and one external floppy drive.

Mac SE: Can accommodate one or two internal and one external floppy drive.

Mac II, IIx, IIfx: Can accommodate two internal and no external floppy drive.

Mac IIcx, IIci, IIsi: Can accommodate one internal and one external floppy drive.

Mac LC: Can accommodate one or two internal and no external floppy drive.

Mac LC II, LC III, Colour Classic, LC 500s: Can accommodate one internal and no external drive.

I don't believe any other pre-USB Mac listed here has an external floppy connector, exception is made for some PowerBooks.

Any Mac with an LC PDS can theoretically have an external floppy drive on it, although that drive will be a 5.25" drive for use with the Apple IIe card. I think I also heard the 3.5" drive for Apple II's will work.

BTW: The LC was very poorly documented, even in its day. The original manual even states that the screen can be adjusted using the brightness control panel!