Valve Equivalents reference lists this as a pentode on B8G (Loctal) base with 6.3V heater.
Brans Vademecum lists many equivalent types including 6SJ7, EF86, EF37A, and numerous others.
Raytheon data shows an alternate higher-current operating condition (Va=250V, Vg=-15V, Ia=75mA, gm=3750, Rp=60000) which appears to be a different tube with the same type number — the GE data at 2mA/1300 umhos matches the small-signal pentode application.