I have no less than 50 NOS 12AV7's & 5965's from various manufactures and the majority are by no means suitable for pre-amp tubes especially in the V1 position.
These were intended for computer/switching use where microphonics was not an issue. I have noticed that there are at least 8 different internal plate configurations on these tubes. The only ones I have ever been able to put in an amp without them squealing like a pig were short plate Sylvania branded.
The 5965 version is even worse.
Data Sheet
Miniature type used for on-off control applications involving long periods of operation under cutoff conditions.
Some data sheets do say suitable for AF and oscillator use, but good luck having that work in the real world applications like guitar amps.
You might find the odd one in the bunch that works, but just remember, if they were any good for audio apps, they would cost far more than $1.99 each on ebay.
Ed