They are great speakers, reviewed in S'Phile a number of years ago. I doubt there are any of those drivers around. I think they may have been designed by Phil Jones. As a long shot you could try contacting him through Phil Jones Pure Sound and ask him for a recommendation for a replacement. I wouldn't pay much for them. You may be able ot get an ok replacement by trial and error, but it probably won't sound as good as what is in there.
Soliloquy 6.5 speaker
I found a pair of 6.5 in good condition everything seems to be fine but i have one damaged mid,any information on this,i know that these are dedicated drivers for the speaker,if someone has work with them or know a replacement for this i know it is hard to find but i know that sometimes few people modified speakers and maybe i can put it to sing,thanks for you help