I belive the good Telefunkens are actually Philips made tubes, which in my opinion sound the best. Very detailed and clear sounding to my ears, though some might prefer the slightly darker and warmer sounding tubes. Good news is they are really cheap so suck em and see...
I have seen a few different Telefunkens, so they were sourced from various manufacturers. The ones i recomend have a very shiny, almost miror like plate inside them... those are the Philips made tubes. Or just buy the Philips branded if you see them.