While looking over tube data, I "discovered" that the 5Y4GA rectifier tube is identical in characteristics to the 5Y3, except for different pinouts. It's also relatively inexpensive compared to the 5Y3 as NOS. So, if anyone wants to build themselves an amp with a 5Y3 sound, they can rewire the socket for the 5Y4GA and get an endless supply of inexpensive rectifier tubes. Less expensive even than new production Russkie tubes.