I wasn't trying to tell you anything you didn't already know. Re-read what I said. Where did I say anything otherwise, and where did I say ALL 6v6 tubes are the same??? How can you even infer that based on what I said? the TAD 6v6-STR, JJ6v6S and Premium Select GT-6v6S Groove Tube are the one in SAME TUBE DESING... all different construction (longer/bigger bottle) from the traditional 6v6, all similar to a 5881 like you mention. The JJ's and Groove Tube's are made in the Tesla/Slovak Factory SAME TUBE. I don't know where the TAD tube is made, but both the JJ and TAD 6V6 tubes have larger plates (anodes) allowing them to safely dissipate 14W rather than the standard 12W. The same goes for the GT-6v6-S. I'm holding one right now, right next to a JJ and a Tung-sol so the visual aid was totally unnecessary too... The only rumor I've heard about this tube type is that it was originally some russian designation that was later re-tooled and the pin-outs to match a 6v6's socket.