We have a total of 4 correct? 2 Before the Cats and 2 After. Are all 4 the same. Because I was looking up some replacement sensors and the part number was the same for all 4!
You avator is disturbing!The fronts O2s are different because they have the heaters and the rears do not. The plugs on the front and rear O2s were the same on my truck.
I know the front are heated and the rears are not because when I did the LTs on my truck I did not use the rear O2s and put them in my tool box for safe keeping. A month or two later my O2s went out and I used my rear O2s in the front. I got an engine code that the O2s were not heating. They O2s worked but just had no heaters.
So the front have heaters and the rears do not.