I think they were Seas 25-- series drivers. They should be labeled on the back. P25 for poly cone; CA25 for paper or coated paper. Also, possibly the 25 fe-w, or 25 fe-w-x drivers. Check with Madisound or Zalytron. There were a lot of models of this speaker offered. Don't jump to replace it with something close if the exact driver is no longer available. There are a lot of these drivers circulating in the speaker builder hobbyist circles.
Good luck,
Steve G.
Good luck,
Steve G.