The 12AV7 tube is a medium-mu twin triode. 5965 is the military/industrial version of the 12AV7 tube.
12AV7 was designed for use at radio frequency and was often found in radios and Television sets.
The 12AV7 does have a 9A pinout, which is the same as 12AX7, 12AT7, and other tubes. Electrically, 12AV7 is a hybrid of 12AY7 and 12AU7. The 12AV7 has an equal mu (gain factor) as 12AY7 but has much higher conductance. 12AV7 can dissipate the same amount of power as a 12AT7 tube.
You can use 12AV7 in place of 12AX7, 12AT7, 12AU7, and 12AY7 family of tubes. It is most effective if used in place of 12AT7 in phase inverter or reverb driver position to tame things.
The 12AV7 tube does use more filament current than a 12AT7. The additional current requirement is small and should be ok unless the filament supply in the amp is near full capacity.
