I think the whole reissue thing needs to be taken with a grain of salt. For one thing, look at an RCA 6SL7GT made in 1945, versus one made in 1975. They're totally different looking, but same curves and performance. There's no telling what tube new sensor actually copied, but I wouldn't be sure that the real Tung Sol had only one version of tube. What I don't get is why someone doesn't license RCA and stick it on tubes. I know I'd eat that right up if I could buy new RCA tubes! For what it's worth, I bought a big pack of 10 NOS Soviet 6SL7 equivalents off eBay for cheap, direct from eastern Europe, and have been using them in ally equipment which takes a 6SL7. I'm more than happy with them, no failures, no microphonics or distortion, just great sound at a low price.