No help to you, but years ago I used to have a Sharp 486 laptop with a PCMCIA 10 Mb network/28.8 modem card in its slot...
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..Until it was nicked at work - along with my nice Fujitsu PCX AMPS phone - while I used a computer in another room.
As much as I'm against corporal punishment I'm tempted to make an exception.
Still, I would have happily forwarded it to you if I still had the $%^&*ing thing.