2007.5 they pushed the DPF's into enforcement. That's when the 6.7's came into service as well.
I think what you'll find with the CTD, is that they are very reliable engines as most people here will attest to. HOWEVER, there is 1 abundantly apparent shortcoming to the truck...
1) The transmission
- The tranny in the 3rd Gens are a common complaint, however it seems to be a common complaint more to diesels, across brands, rather than a Dodge issue. It seems the 4th Gens are getting descent reviews on the new transmissions... This is all 3rd hand information, I only have a 3rd Gen Dodge. No experience with a 4th. On this note, people who have refrained from over-extending the performance of the 3rd Gens using programmers or the like, seem to be quite happy overall (as I am).