I've heard about the "problems" with the 6.0l. Is there a "best year" for this diesel in a SD 4x4? Or perhaps is there a learning curve that cured most of the issues by a certain year model? Im wanting to replace my '99 5.4 with something newer. thanks.

 

2006/2007... but only because they're the newest ones time wise, and 05-07 IMO look the best to me. They're pretty much all the same at this point, 10 years of use has a way of averaging out all manufacturing problems and making each unit an individual.

Read this and apply to each individual truck, try to avoid generalizations and focus on that one unit:
https://www.ford-trucks.com/forums/9...used-6-0l.html

 

2005-2007 is what you want to prioritize, but there's some good 03-04 trucks out there. The thread that texastech linked to explains the differences between each year very well.

The 6.0 problems exist, but are often exaggerated. A well maintained 6.0 can be nearly as reliable as the infamous 7.3. The main problems are the stock EGR coolers and the head gaskets.

This one is also another excellent source of information:
https://www.ford-trucks.com/forums/3...ch-folder.html

 

There were many non-engine differences between 2003-2004 and 2005-2007. The switch from leaf springs up front to coils, bigger brakes, and the available tow controller are some biggies.
From Ford Super Duty - Wikipedia, the free encyclopedia

The Super Duty line was restyled for 2005, with the exterior and interior receiving minor updates. The dashboard, gauges, headlights and badges were all updated, and a new, taller front grille, a revised interior and a standard locking tailgate were also added. Significant changes were also made to both the drivetrain and available options.

Major changes over the previous generation of Super Duty trucks include increased payload (GVWR) and towing (GCWR) capacities.

10-17% thicker partially boxed frame, alternator with a higher current capacity.
Larger 4-wheel disc brakes (13.66-in front and 13.39 in (340 mm) rear rotors) with new two-piston calipers.
Coil spring front axle for improved turning radius.
An optional built-into-dash Ford TowCommand TBC (Trailer Brake Controller) that is fully integrated with the truck's PCM (Powertrain Control Module) and ABS (Anti-lock Braking System)
Optional dashboard-integrated auxiliary "upfitter" switches (for adding off road lights, winches, snow plows, etc.)
Optional drivers side glove compartment.
17 inch wheels are now standard instead of 16 inch wheels (due to the bigger brakes). Forged Alcoa wheels are still an option as well. 18 inch wheels are also an option on single rear wheel trucks.
4x4 outer axle shafts got bumped up in size, standard 30 spline axles are gone in favor of 35 spline shafts.

Fuel tank capacities are 38 U.S. gallons in the 8' long bed models, and 29 U.S. gallons in the 6.75' short bed models. Depending on models the optional trailer tow hitch receiver comes with a 2" or 2.5" Class V receiver and 4- and/or 7-pin wiring harness in either 12,500 or 15,000 lb (6,800 kg). All Super Duties include factory installed external oil and transmission coolers.

 

The best truck is the one you have the title for. I prefer the leaf spring front end. None of them are perfect.

 

trying to learn as much as I can, so can I ask why? 4 wheelin actuation?

also any idea if the coil type "tighter radius" is effective with larger tires?

 

It's simple and it works. It's a straight axle front end, not exactly high tech.

 

Take into consideration with a lift and tires on a leaf spring truck you have a chance of tire rub on the leaf spring pack @ full turn.

My vote is for 05-07. The early 04.5 and down has the failing HPOPS (even rebuilt from Ford), I'll take the more reliable pump. Plus the 05+ has a better looking front end and interior in my opinion. And of course as I mentioned above, the coil front end. Oh and don't forget the upfitter switches, integrated brake control, backup sensors, and adjustable pedals.