If you would live close to me, you could find what you need in my basement. I have 3 big boxes full of fans, some used, some new. I am a noise freak, noise drives me crazy, so I'm always replacing the cooling fans on my computers and padding them with resistors to quiet them down. Right now I have 7 working PC's and I've been working on computers for over 23 years. That's why so many fans.
To replace the fan all you need to match is size and voltage. And the amps will determine your RPM and therefore your CFM. If noise is not a problem for you, you can go with a higher AMP/CFM. That will keep things cool and happy.
For the connection, you can cut the connector from the old fan and put it on the new one. You only need to connect 2 wires. One is positive, usually red, and the other negative, usually black. Any extra wires you can cover with tape and leave not connected, they are sensing wires that your inverter doesn't need.
As for brand or quality, I have found that Delta and Sunon are usually better quality. But any fan will last you many years.
If I were you I would replace both fans. The one that is still working could follow his twin brother to the fan graveyard soon.
Ed