thanks Joe, that was more help than I got from talking to everyone else.
I called the dealer today, they did replace the rear bank. I told him what you said and he keeps telling me the the A/f sensor is not on the manafold, and he said they did replace (I think he said) the ASM I told him I don't know what that is, I thought you replaced the O2 sensor and he said yea that is the o2 sensor. when I told him the o2 sensor is on the pre cat he said no it's on the manafold.
maybe this guy is just confusing what sensor is where and I'm going to bring it back to him.
at least now I'm armed with a little more information, thanks to Joe