The 6GE8 (P/N 154-0260-00) is a triode-pentode combo tube with a B9A (Noval) miniature 9-pin base.
The 7734 is the high-rel version.
It's an unusual tube. Most triode-pentodes contain a small-signal triode. The 7734/6GE8 triode is designed to dissipate some power, typically as the pass element in a linear power supply regulator.