I think that's one of the first years for the DPF...if not the first...
IMHO... I would steer away from any of the big three first year DPF trucks.
I recommend going for a truck a little newer and getting the DEF and DPF... the MPG is better and the manufacturers figured out the new emissions better.
Just google 2008 Duramax DPF and read all the users wanting to get rid of the DPF on these trucks.
Another option is to go with a little older truck...2006 or 2007...considered to be one of the most desirable Duramax years.
Thanks, and again....JMHO.
Jeremiah