It is funny that you bring it up Mordy, I read the same bit from Jac, but I have not been able to find any other source stating the same as far as the Toshiba-Telefunken connection goes. He is referring to the 6SN7GTB specifically.
From his price list, he says "These look so amazingly similar to Telefunken 6SN7, perhaps it is no coincidence. Well it is
just a speculation, but it looks like this to me."
I don't own the Toshiba, I purchased one for a song, but the seller sent me a 6V6 instead! Got a refund, but didn't follow through on getting the Toshiba.
These are the Japanese drivers I own, Hitachi 6SN7GTB, Hitachi 12SN7GT, Nippon Electric 6SN7GT (PRC rebrand), Nippon Electric 6SN7GT (although looks identical to -GTB).
And the two types of RFT tubes. If anything, the PRC-rebranded NEC 6SN7GT looks more similar to me with it's solid plates, but I think it is just coincidence.