Yes, Soliloquy has been out of business for awhile. I don't know about the 6.5's but I've had the 5.0's and SAT5's and the drivers were proprietary in both of them, there are no commercially available exact matches.
Underwood HiFi, who advertise here on Audiogon, bought some of the remaining stock when Soliloquy went out of business and had a few replacement drivers available for awhile. You should contact Walter and find out but I wouldn't get your hopes up.
You might find a close match at Madisound or Parts Express but as Cleaneduphippy suggests, getting help from someone who understands the implications of using a different driver would probably be a good idea.
Underwood HiFi, who advertise here on Audiogon, bought some of the remaining stock when Soliloquy went out of business and had a few replacement drivers available for awhile. You should contact Walter and find out but I wouldn't get your hopes up.
You might find a close match at Madisound or Parts Express but as Cleaneduphippy suggests, getting help from someone who understands the implications of using a different driver would probably be a good idea.