Wow.. you're right -- just be sure that the new driver is the exact same if you want to use the old box. I will look into possibly swapping in new drivers (why not, so many have been updating the tweeters to Seas or Morel).

Switching caps and playing with the xovers shouldn't be too tricky; do they recommend using the old boxes with the same aperiodic vent (sorry if you guys posted this above).

I love the way mine sound, but there's little doubt that much has been improved in terms of driver design in 35 years.