I usually tend to use 5U4GB’s as the rectifier when needing a high current tube rectifier. Their are a lot of NOS ones on eBay as well as good used ones for a low price. The downside to this tube is the voltage drop which is in the 50 volt range. I tend to specify the power transformers to use this tube and voltage drop as the target for voltage out of the power supply so I can move the voltage up with GZ34’s or even, dare I say it solid state rectifiers. I like these tubes, they are big and look good in pairs as used on the EZ260 and EZ125. Again, they are not the most efficient, but that’s now what using tubes is all about. For amps like Dynaco’s I have stuck with the GZ34’s as that was original in them.
If the page is blank click here GE 5U4GB Datasheet