I have done a bit of hunting so far and since this particular version of the 8340 has been discontinued since about 2005 I may be out of luck on a new replacement. The 8340A with the plastic cabinet and screw on driver came out before 2001, and I think the wood cabinet version changed over to the newer driver in the same time frame before they stopped making it alltogether. If one does turn up, I will use it.
Until I can find one though, for $12 each, I think this one might get me in the ball park.http://www.mcmelectronics.com/product/53-1270
I have been a cinema sound installer for many years, and I know the different driver specs, even though small in this case will result in a different slope and balance especially around the x-over frequency. If I was trying to match other speakers, it could be a problem, but since it is just my 3 single speakers, and I have Eq for each one, I do not think the issue will be a problem at all. Worst case, I might have to adjust the impeadance matching section of the x-over. And since I have the full schematic of the x-over, I should be able to work that out once I sweep the new driver. At this point I think I am going to try the new horns in left and right, keep the JBL one in center and see how they compare. This will also give me a good spare for the center channel.
I just did a frequency sweep on the left and right horns, the level out of them is over 6 db different at the same drive voltage, and the current is almost identical. It appears the magnet has just lost it's strength. Just sticking a hunk of metal on the back and pulling it off, it sure does feel a lot weaker. I have never had a speaker demagnatize on me before.