just this quick question i have looked in the tube sticky
Yes and no. 5881 tubes were military grade 6L6 tubes. Real 5881 tubes are not made anymore but tungsole makes something that is really close and marketed as a 5881. Most modern musicians that are after vintage tone find the tone of the tungsole 5881's to be "too cold" but hardcore vintage guys seem to love them in their tweed style amps. There are many companies that make "short bottle" 6L6 tubes which have a tone that is a cross between a 5881 and a 6l6 that tend to be much more popular because they have smoother distortion and a more controlled tone. I'm particularly fond of the TAD short bottle 6L6 tubes. What I would refer to as a "real" 6L6 tend to have a "chunky" distorted tone and the break up sooner than the short bottle 6L6 or the 5881 tubes. Tone is all preference so your best bet is to get a few sets of tubes and play around with them. Then sell the ones you don't like on ebay. If you don't scratch them up you could even sell them as new.