Thanks for vote on the PT originality. From what I can find on internet the 6516 was an early tweed Twin transformer - 5C8. Again, weird. Looking at the way it's wired in, and the solder joints, it definitely gave me pause. It's a 6G4-A circuit. 6 preamp tubes. 68k resistors tied to input jacks. Re: voltages: I've got -57 at the bias supply cap. 455v on plates and 32ma bias. That's pretty darn close to spec and I'm certainly not alarmed by those numbers. Will post more pics of transformer wiring at rectifier when I have it open to replace filter caps this weekend. Thanks to all who've replied and for your enthusiasm and expertise. It's been fun sharing my new toy with you all.