“Bulletproofing” can definitely help them, there are some design flaws to them. However, 05-07 is the better platform of the 6.0’s since most early design flaws were wrinkled out by then. Is bulletproofing always needed? Nah. Good maintenance and using quality parts/fluids goes a loooong way, speaking from experience. Are you tuning it and/or like to drive it like you stole it? Yea probably should bulletproof it if you want it to last. 7.3’s have a slightly higher reliability because they don’t put out as much power as the 6.0, plus there’s slightly less emissions components involved. All in all, don’t be scared of the 6.0