I have a '04 E350 extended cargo van with the 6.0 which I put 235k miles of basically trouble free miles. I came to this site when my alternator siezed and broke the serpentine belt so I asked how to replace the serpentine belt & started reading horror stories about the 6.0
The one thing I learned was the E series engine is de-tuned from the F series trucks which I believe has saved me the grief others have had with the engines in the F series.
FWIW: E series puts out 235HP @ 3150RPM & 440ft lb torque @ 1600RPM
The F series puts out 325HP @ 3300RPM & 560ft lb torque @ 2000RPM according to literature I've read.
This was my old work van and all I did was change oil between 6 & 10k miles & I think I'm on the 3rd or 4th fuel filters. Driven mostly interstate @ 70+mph.
After reading all the great info on this site, I'll be taking better care of it and change fluids etc. at recommended intervals.
I for one... love this truck!