I drove a 2007 3500 quad cab dually all over the country towing and did have emissions issues, but this was the first year for the 6.7 engine. My biggest problems were the junk G56 6-speed transmissions, went through three of them, and also a South Bend clutch that was junk, thought I had upgraded but I was wrong. If you go diesel buy a 2010 or newer automatic.