I managed to unearth some new, matched tubes. Get em while you can!
The Sovtek 5881WXT is the same as the 5881 but with a full size base for easy installation in vintage amp designs. The Sovtek 5881 delivers a warm, round tone that "sweetens" any vintage or modern guitar amp design.
Built to rigid military standards, the 5881 will tolerate higher voltages than any other 6L6. In fact, they're frequently used as replacements for the old 7027 model in vintage Ampegs. Extremely consistent from piece to piece.
The Sovtek 5881 has a heater voltage of 6.3 volts at 0.88 amperes.