Great, that answers that question. Bank 2 is drivers side. They guy at Autozone had it backwards. Too bad I killed the old sensor that I replaced. Anyway, to answer Mike's Question.
Replacing the rear O2 sensor is pretty easy. The only hard part is redirecting the cord back to the engine. Also, they can be hard to get out. I bought a special oxygen sensor socket, but there wasn't enough room to put that in, so I had to use a wrench. Needless to say, by the time I got it out, the old sensor was dead. Anyway, I suggest doing it yourself rather than paying someone 250 bucks to replace it. You can buy an OEM part from Autozone for 68 dollars. Worst case scenario, if you can't replace it yourself, at least you only have to pay for labor on the installation. Nissan is charging 160 dollars just for the part.
Mike