IMO, get a 3500. I few days ago I got a check engine light NOX sensor circuit performance performance bank 1. I cleared it and have put a few miles on the truck going up my local grade at 2500 RPM. The code has not come back yet, but I was getting ready to leave on an interstate trip. I don't know if this will cause the truck to go into a 5MPH countdown mode or not like a bad DEF code will. The bad DEF code is another issue, I put DEF in before my trip and drive around for a few days to see if I get a code. I love the Cummins engine, but I don't trust this truck.