[Jeff]

Joffe has used the Walker brand and has had no problems, iirc. Of course Bosch is the recommended o2 sensor from Nissan.

 

[Jeff]

Funny...my rear 02 went out around 50-60k as well. I'm at 80k right now and haven't had a problem with either of the front 02 sensors. (knock on wood)

I wouldn't say go ahead and replace the other as a preventative measure. They aren't like headlights where if one goes out the other is soon to follow. I don't even think there is a 'typical' life span. *shrug*

If you have the money to spend though then go ahead and replace both...along with your KS and coolant sensor and TPS. (just kidding)

 

[Jeff]

Well I wouldn't say it really takes a lot of time to replace an o2 sensor...less time than changing out leds for sure.
, haha

The other could go bad in a month or it could be 2 years, that's the general consensus.