First off, your truck has 3 million miles on it? oke:
Second, I understand the fear that something might break because it's a high mileage truck. If something is going to break, it's going to break no matter what. EFI Live tunes just may cause breakage sooner because you can't keep your foot off the go-fast pedal. But EFI Live itself will not be what breaks your truck when those tunes come from a reputable tuner like Kory/Rob.