As with everything.... The more stock you can find the better. As mentioned some people get rid of problems and lift kits can be come problems if they are not addressed. I would not want to buy a truck that was lifted. I would however lift my truck just would rather be the one and know how and who did what was done. The same goes for tuning devices and any add on electronics. While buying a tricked out truck is appealing and can save you over buying the parts your self it is a gamble that the truck was done right and that there arnt gremlins with in

 

Another thing to consider is the fact that a 5.4 vs 6.8 (v8 vs v10) on the gass engines is the mpgs.... They are so close in milage I would never even consider a 5.4 truck. Reguardless of who has pulled what the v10 will do it better. The psd is a great choice as well. I love my 6.0 and get good mpgs unless I'm towing but even the I'm 12-13mpg

 

Data point:
I use the truck in my signature to tow our Nash 22H trailer. 4522 pounds dry (per scale, not sales literature). For week long trips to the dunes, we haul it fully loaded (close to 6K pounds), along with a bed full of firewood and water (70 gallons) and two quads sitting on racks on top of the bed.
The truck is using F-350 blocks in the rear and 3" lift springs in the front.
We use Equal-i-zer WD/antisway hitch.
She tows like a dream - even with the tall sidewall tires.