To be shot in two years, sounds like you've got a short in a circuit that is causing a high amp draw when you leave it parked. Try hooking up an ammeter between the positive battery terminal and the positive cable (been a long time since I've done this, hopefully someone can chime in if I've...
With all the drama over the last few weeks, I've missed a place to just hang out and learn more about the 6.5L. Since most of the knowledge has transferred over to here, I'm hoping this site really takes off.