Bubba, hi. The source I checked has 5Y3GT with max 350V 120mA, GZ34 350V 160mA, so 5Y3 40mA lower for max Amp. Might stress tube if set is drawing over the 120mA. PL
:Is it OK to substitute a 5Y3 in place of a GZ34 and vice verca? I have heard conflicting reposrt on the idiot-net. I have a Dynaco. It seems to work fine with it.