anyone have to replace these? how long did it take and how hard was it.

 

Pull the intake manifold and they sit right on top of the block. Takes a few hours but it's not hard at all

 

What year vehicle? I believe 800 has sensors located as described above. GMT900 had sensors noted below.

Do you have codes to determine which sensor; 1 or 2?

DTC P0325, DTC P0327, DTC P0328 relates to sensor 1

DTC P0330, DTC P0332, DTC P0333 relates to sensor 2.


Sensor 1 is located on the lower left of the engine, sensor 2 is on the lower right. Not sure if manifold has to be removed; from memory I believe you can access them from under the vehicle since they are located toward the bottom of the engine.
Might have a picture...