One of the most commonly found driver tubes found in push-pull tube audio power amplifiers is the 12AU7 tube. As well, this tube's low gain make it a great choice for tube preamps in hi-fi stereo systems. They are found less often in instrument tube amps but Ampeg is one manufacturer who has used them for years as drivers for their SVT bass guitar amps. Other common names for this tube are ECC82 and ECC802 and the European special-quality E82CC and E182CC. Names found in military and industrial applications are 5814, 6189, and 7316.
Be sure to click the “Additional Info” tab when viewing a specific 12AU7 / ECC82 / ECC802 tube. There you will find related articles and downloads such as datasheets, pin-outs, ratings, and matching information when available. Other excellent links for technical information can be found at 12AU7 in Wikipedia, 12AU7 in Duncan Amps, and 12AU7 in The Tube Directory.