Yeah none of those would work. It's such an unusual configuration that there is no aftermarket application for it. Not that you'd want an LED in there anyway.BTW if you wanted LED's, check out this site http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=/1157.htm
Yes, and LED leads are the perfect length. Just take the bulb out of the holder and slide an led in, get the leads in the hole and there ya go. Worked for me...It is a bulb with very long leads. I ended up finding some bulbs at radioshack, and twisted the leads to how there were in the stock bulb on the brown rubber piece.
Heres another thread on the subject.