JAN-Philips 5751 Review.

While not really a 12AX7, it shares the same pin-out arrangement and is designed for less gain in favor of lower noise and microphonics. It worked well in both test amps and can be used to advantage if your amp has too much grind. One of these should calm things down a bit. The 5751 is an affordable alternative to the 12AY7 used in original Fender tweed amps and can be subbed for a 12AT7 like a reverb driver tube. In this application, you will get good gain with a warmer sound than the 12AT7. The even balancing makes them a nice phase inverter and allows you push the front end of the amp a little harder.
Information from thestoretube.com