Had an upstream O2 sensor fail on the 2001 Durango last weekend.  Attempted to   
   do the repair myself and gave up after a few hours.  The O2 sensor was seized   
   in the exhaust pipe.  600 pounds of torque, torch, nothing would get it.     
      
   It was also in a difficult spot (on top of the exhaust pipe facing the bottom   
   of the vehicle).  I have a special tool to remove them in that situation, but   
   it was stuck.   
      
   Took it to the shop for them to do the work.  They were also unable to get it   
   out.  Felt a bit better about my attempt after I heard that.     
      
   They are going to drill a hole and install a part that basically creates   
   another O2 sensor hole to screw the new on into.  The only other option was   
   cutting that section of pipe out, which would have been more costly and time   
   consuming.     
      
   Several years ago, I replaced the O2 sensor in my Monte Carlo without too much   
   trouble.  The main difference was the upstream O2 in the Monte is basically in   
   the engine bay and not on the bottom of the pipe near where all the rust   
   happens.   
      
   - Mark   
        
   --- WWIVToss v.1.50    
    * Origin:  http://www.weather-station.org * Bel Air, MD -USA (1:261/1304.0)