KEF vs TDL drivers

Still looking for that other pair of B-139's at a reasonable price.
Does any body know what the model number for the later driver is?? and when did manufacture change??
TDL looks like they may be starting up again

link to driver
Any clues to changes in parametres ?? also if this driver is so good ( awful cone break-up at k1.5 for the SP 1044, not-withstanding) why did manufacture stop??
I like the driver as much for the narrow profile as anything else, What would this driver sound like if remade using modern technology?? i;e: vented voice-coil, shorting rings extended pole piece etc:
Yes the TL page has links to a German kit site but i have been unable to find any information on the actual specs of the driver itself
This site quotes frequency range down to 17Hz ( at what level??) so i have to assume driver parametres are quite different.
I had always assumed that Elac developed the original Bi-radial driver, if you look closly at some of the later IMF boxes they appear to use this woofer.
I now have two pairs of B-139's so need to make a start on the next box or the wife will slaughter me for spending some of the honeymoon cash on drivers, I was just wondering if there was any information in our extended community on the differences.
No body ever went broke catering to the masses, what does the average meat pie taste like??

For all but the Aussies here a meat pie in Oz is like fish and chips in England and hot-dogs in America and I would prefer not knowing what goes into most of them ( I like a good meat pie, haven't had one in years )

But seriously has no-one ever tested one of these to compare to the B-139??
Just had an Email, this German company still has a few of the TDL drivers in stock

Quick question, if I was to my existing KEF drivers in a sealed box and wanted to lower the resonance a little how do I caculate how much mass to add to the driver??

B-139's have that flat face so it should be relatively easy to glue multiple layers of heavy paper or felt to the front to do so but i would like some idea of how much I need to add