RW> Yes, it has 4, two before the cat and two after. Dual Exhaust, you know.   
   RW> We found that one of the after cat sensors was the one signaling the   
   RW> computer to err, but it checked out as good in up close testing.   
      
   My daughter's old car had a similar issue with the O2 sensor after the cat.    
   In her case, however, the cat was probably not functioning as good as it   
   should have.     
      
   To save spending a fortune on a new cat, I bought offsets for the O2 sensor   
   after the cat.  That allows it to still get a reading, but not as much as   
   being directly in the flow.  They are used for people that remove their cats,   
   but don't want a check engine code up all the time.  :)   
      
   RW> Be sure you check which engine the later models have. The 97 still had   
   RW> the 5.7L, while the 99 could have either the 5.7L or the new for 99, 5.3L   
   RW> LS engine. GM got pretty close to perfection on the 97-98 fuel injection,   
   RW> then switched to the new design in 99 and full on LS engines after that.   
   RW> My high school buddy in Illinois bought a 2007 Tahoe and it came with the   
   RW> smaller size 4.8L LS, the same one that's in my 02 Silverado. He tows a   
   RW> boat and trailer and was disappointed that it downshifted to 3rd on   
   RW> hills.   
      
   In this particular case, it was the 5.7L.  They have both a 97' and 99' at the   
   local auction and they are still there.  $1900 for the 97' and $2100 for the   
   99'.  I was tempted on the 99', but the A/C wasn't functioning.  Everything   
   else checked out.   
      
   RW> All Girls Garage pointed out that the Toyota Tundras have the same   
   RW> problem. They blamed the blower motor speed resistor, which is probably   
   RW> your Durango's problem too.   
      
   Yes, it is a very common problem with them.  Last time I went to a junk yard   
   just looking for a few items, you could see where the Durangos and Dakotas had   
   their resisters, wire harness, and blowers stripped already.  I had finally   
   located one way in the back that still had the wire harness, which I cut out   
   to remove and installed in our Durango.  The old one had melted and fused   
   together really bad, enough to short wires.   
      
   - Mark   
      
   --- WWIVToss v.1.50    
    * Origin:  http://www.weather-station.org * Bel Air, MD -USA (1:261/1304.0)