FYI, after looking all over town for a downstream O2 sensor for my "95" Maxima that fit, I found out that it was a part number for a '94 maxima, which I thought did not have the O2 sensor in front of the cat converter.

Maybe this will help someone else.

Also, this also took care of my Knock Sensor diagnostic, which was referenced in some other threads.

I saved a bunch of bucks on this one; I think my mechanic would have changed both.