I know a couple people who had '03 6.0 trucks and had problems, but I had an '04 and '06 F350 with that motor and put over 100K on both with absolutely no issues what so ever.
I am currently driving a '09 F450 with a 6.4 and have 80K on it with no problems.
I have heard of good and bad in every brand and with every motor.
