Same Loctal pinout (8V) and remote-cutoff pentode but higher heater current (0.3A vs 0.15A) and different operating characteristics — Raytheon lists as substitute
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max Plate Voltage300V
Anode Dissipation (max)Max Plate Dissipation2.35W
Screen Voltage (max)Max Screen Voltage100V
Typical Operating
Anode Voltage (typical)Plate Voltage250V
Notes
Remote-cutoff (variable-mu) pentode for AGC-controlled RF/IF stages.
Max plate dissipation 2.35W, max plate voltage 300V, max screen voltage 100V (GE data).
Brans Vademecum lists extensive equivalents in table Vb including 12SK7, 6SK7, 6BD6, EF39, and many others — these are Octal/Noval base types and not pin-compatible Loctal drop-ins.