Replacement speaker Driver Seas CB17RCY or CC17RCY Ruark Talisman 1 speaker

Hi Im Looking for one replacement speaker for one of my Ruark Talisman Speakers it can either be a CB17RCy or CC17RCY or an Equivalent,Its a 6.5 inch MId/bass driver at present its been replaced by someone with an Altec Lancing on one speaker which dosnt sound as good or even balanced with the original speaker in the other cabinet,so any help would be appreciated if anyone knows of a suitable replacement,it has 4 fixing holes not like the modern seas with 6 also higher sensitivity at 91db
Regards in advance for any help Malcolm