The 6.0 has an issue with the EGR. It is quite common. Two of the three 6.0 owners I know have had it go out, the third deleted his before it did go out. There are options out their to delete it to avoid the issue. The 7.3 was a much better engine. Once the 6.0 is patched it is a very good engine. The Dodge 5.9 has its issues too. The stock lift pump is prone to failure which starves the injection pump causing it to fail. The lift pump should be replaced with a high flow aftermarket unit ($850 installed). The injection pump is $1000 alone, not including installation. Also the Autos in this years are sub par and should be upgraded if planning on doing any towing. I own one. The early Duramax are plagues with head gasket and injector failures. I knew a guy who replaced three sets of injectors each at 40k miles before dumping the rig. Plenty run just fine though. All of them have issues, pick your poison and be prepared.