My car came with a single wire O2 sensor i wired in my own heated O2 from a GTP 3.8 engine but the sensor from the 00 grand am looks like this
this is what mine looks like now
here is one easy way to install a heated o2 sensor in our cars
http://www.casperselectronics.com/mm5/merchant.mvc?Screen=PROD&Store_Code=CEI&Product_Co de=103025&Category_Code=
i didnt buy this but if you save the picture and open the pic from your picture file you can enlarge the pic so that you can see what they did to make it work and how you can make your own harness its very easy.
i was trying to find the wireing diagram for the to years but i cant find it now, so i can try to give a more direct wireing spec of it. It shouldnt be that hard to do plus i dont think i will make a difference but dont quote me on that, i really dont know if it will but it shouldnt.