Good deals on these
If it has the latest reflash (EGR and cold start reprogram), you should be good to go. The earlier 6.0's got a lot of negative press, and somewhat deservedly so. However, if it has been taken care of (filters, oil changes, no chips or programmers) it might be a great bargain. Many folks would advise to get head studs and EGR delete if you are going to be doing hard towing applications (or even DD). One of the good things about the 2003 is that IIRC they are more amenable to EGR mods since the CEL is less of an issue. There are some way more experienced folks on this board, so it should be interesting to see what they have to say.