I got one of each and, love em both and i work on all three brands at work. True the 6.0 had problems in the 2003 and 2004 model years, and they were hit or miss problems. My 05 has had no problems yet and i love it. To tell you the truth i worry more about my cummins having problems than my psd, because of the 53 block, the vp-44 and the transmission(waiting to install my transgo kit). My psd i dont worry about anything, even though its still under warranty. Plus the majority of headgasets were on the highly modded 6.0's, so folks put studs in them and they hold up great. The other problems are the egr valves and the egr cooler. Both problems can be taken care of with a few mods. So the later 6.0's (05+) were solid motors. The 7.3 were great too the only trouble they had would be a cps going bad which is just a 20 dollar fix. Oh and the comment that it would suck to work on them because of the tight space is kind of true. The cab has to be lifted for several repairs like headgaskets, some guys can get the cab off in little over an hour though.
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2005 Ford F-250 Powerstroke. 1999 2500 extended cab short bed, edge ez, staight piped, silencer ring removed, walbro fuel pump, Diprocol fuel, boost, and pyro. gooseneck, 15% tint, transgo kit, a new western mvp v plow on order!!! and a 53 block