I like to run 5w-40 Dexos2 oils in my 2.8l Duramax. Other than ordering them on-line, they are very difficult to fine locally.
It appears that NAPA now has Havoline ProDS full synthetic 5w-40 in some stores. If not I assume they can order it. I'd give it a try. Waiting to see if they will run a special like they do on the Valvoline MST 5w-40 Dexos2.
Has anyone out there purchased this? I'm not sure how long it's been available, but I found it while searching Fred's Tdi forum.