Hi new here hope someone can help have a 2006 silverado ss and trying to hook up a AFR gauge but i do not know witch wire is the O2 signal output wire coming out of the ecu the gauge is a prosport don't really care about the accuracy just want it to work can someone help thanks!!!

 

You're not going to get the result you're looking for while using stock narowband sensors. Research "wideband".

 

I take it back. Checked their site sounds as easy as hooking up guage as you have asked, unfortunately I don't know the answer to your question.
-Good Luck