2013 up series is almost completely different from 2012-back. Much less trouble from emissions, better power, frame, brakes, load capacity. Before 2013, the Aisin was the 68 series and only in chassis cabs. 2013 up the Aisin is the stronger, improved 69 series and available on 3500 pickups as well as the chassis cabs. I had planned to keep my early 2004 "forever" until the 2013 came out, huge improvements.