Marybeth:
I got my 06 Dodge Cummins done here in Sacramento in August. I was sweating it because when I originally bought it, an aftermarket accessory installer said that the catalytic convertor had been removed. Sweating this before the test, I called Swift Dodge's parts department in Davis with the VIN number. They checked and told me this truck, originally sold in Arizona, did not come with a convertor from the factory.
The test was a breeze, as stated before - mainly a visual test for smoke, although I thought it WAS connected to the test machine for a while. Probably to automatically transmit the results to the CARB and the DMV.