I am sure you know the issues with the 6.0 and 6.4, but they are a bad investment. Even if you dump the money in them to make them run, no one wants one. You cant give them away. A 28K 200K mile Duramax is silly, but it shows how stong the preception of that truck is, even if you dont like GM trucks, anyone that knows anything about pickups knows its a great powertrain. Buy a Dodge if GM doesnt do it for you, but putting money in a 6.0 or 6.4 is equally as silly as buying the 200K Duramax.