Thanks @Wes_S for the pointer to those “real” used bad boys on Ebay. The Philco rebranded one arrived today. Sorry, for the rest of you, no, it’s not going on sale here for half price. It is audibly more open than either the original TungSol that came with my Lyr3, or the RCA 5692 Red Base that I have been using. I have not listened long, nor do expect to get rid of the RCA, which was NOS.
It’s interesting to compare the construction of the three tubes. The RCA is clearly more shielded, and in an electrically noisy environment, I would not be surprised if it came out on top. The Philco/Sylvania and the TungSol are both taller, and have more slender construction. The glass on the Philco/Sylvania appears to be clearer and more delicate.