Thanks - I have not tried buying from Europe yet. From now I will be willing to give it a try. But now I already have the 50 PN4393s coming. Also - just FYI, the picture of the ones I'm getting appears to show them to be fairchilds.
Yeah, there is a bunch of sellers in the former Eastern Bloc countries, who are the only source of the Soviet military Germanium components that so many of us are addicted to. They are the ONLY suppliers of these parts as far as I know - no one in the States seems to have cottoned on to buying some of these parts in bulk, then re-selling them.
So if you want Soviet Germanium transistors like MP 20s and MP38s, and diodes like D9 series or D310 / D311, then you will have to order from Bulgaria, Romania, Russia etc.
I've never had a bad experience buying from these guys - unlike some of my Chinese purchases!
My guess is that swapping ALL of them is not the same as swapping one of them. To say they are fully interchangeable suggests you can use either one any time you want - its just a matter of semantics that I think should be clarified - whether or not you should strive to match the pairs since Jfets generally work in pairs somewhat emulating the "push-pull" gain of output tubes (which always come as matched pairs).
If John said he 2N5457 for his build, I can almost guarantee that he used them in ALL positions. If he then said that he swapped them for the originals, and heard no real difference, then I would believe him. He has a LOT of knowledge, skill and experience doing this.
I would read through his comments on this layout, the Catalinbread DLS MkIII.
They might help - there is not a lot of difference between the two circuits really.