I own a 1996 3500 4x4. This year the great state of Az. failed my truck. i have a 5" exhaust and no cat. I installed the exhaust system myself, there was no cat on the stock system I removed, only a resonator and a muffler. I went to both of my Dodge dealers with my V. I. N. . The dealers both pulled up my build sheet that shows a code ( NBL) delete EVAP Control System. Which they both told me that it did not have a cat. from the factory. I went to the referee station with this build sheet and information in which they replied " it does not matter because you have a catalyst number stamped on the motor. I called Cummins , posed the question,they ran the C. P. L. # and said it did not require a cat. . In fact I gave them the catalyst # stamped on the motor (26233). They could not find any match for this # in any of the searches. I"m trying to fight this insanity. I put one (cat) on to pass and stopped inside and asked where they are getting their info from as I had read the emissions law online and their reply was" if is not in the Az. law they go by the Mitchel manual". Huh?Can anyone help me with this? Thanks!!!!!!!!