2004-2005 have a thicker front bumper air inlet, as seen in the link below:

http://gtcarlot.com/colors/car/69404107-6.html

2006-2008 thinner air inlet seen here:

http://gtcarlot.com/colors/car/12344200-7.html

2004-2005 have squared/rectangular fog lamps, while 2006-2008 have circular/round fog lamps.

2004-2006 models with two-tone paint (Lariat, King Ranch) have Arizona Beige Metallic as the lower accent color, 2007-2008 models have the lighter Pueblo Gold Metallic accent.

2006 Arizona Beige Metallic:

2007: Pueblo Gold Metallic:


(Both images shown on a Dark Copper Metallic King Ranch for comparisons sake.)

2006-2008 models get Sirius Satellite Radio as an option, which adds a small antenna on the passenger side of the roof.

2006 also adds the ability to order the longer 6.5-foot cargo box/bed with the SuperCrew cab configuration. This also adds the ability to order a SuperCrew with Flareside bed for the first time (these trucks are quite rare). A new six-spoke 20-inch wheel is also optional on Lariat, FX4 and King Ranch starting for 2006.

Chrome package: for 2006, the chrome package on XLT and Lariat adds 18-inch chrome-aluminum wheels, 5-inch chrome tubular step bars and chrome exhaust tip. It also adds a black honeycomb grille insert, chrome tailgate handle, door handles and chrome mirror 'skull-caps' exclusivly on Lariat.

For 2007-2008, the chrome package also included a unique grille for the two trim levels. XLT was given a chrome 'H-Bar' style grille (seen below).



Lariat offered a chrome 'billet-style' grille (seen below)



2007 also saw the introduction of the FX2 Sport package.


2008 offered a special XLT 60th Anniversary Edition, celebrating 60 years of the Ford F-Series truck. This package was only available with a unique Dark Shadow Grey Metallic and Black Clearcoat two-tone paint treatment. Special badging also adorned the truck's front doors and tailgate. (seen below)



2008 also added the luxurious Limited trim level for SuperCrew F-150s with a 5.5 foot cargo box. Only available in White Sand Tri-Coat Metallic, the Limited features chrome boxside lettering, a unique grille and massive 22-inch polished forged aluminum wheels. (seen below)



Harley-Davidson edition was new for the 2006 model year on SuperCab trucks with a 6.5 foot cargo box. For 2007 the package was expanded to SuperCrew 5.5 foot box trucks as well. 2008 added a new Monochromatic Black paint scheme with Unique Graphics or an optional Black and Vintage Copper two-tone paint scheme. This celebrated the 105th Anniversary of both Ford Motor Company and Harley-Davidson Motorcycles.

2008 with Vintage Copper paint shown below:

Now I will talk about some other options packages/special editions only available in limited markets.

Targeted for the Latino market in the United States, Ford offered a special edition Lobo F-150 to its Texas dealers in 2005. Based on a SuperCab STX with 6.5 foot cargo box and two-wheel-drive and only available in Bright Red Clearcoat, the Lobo carried a base price of $26,355 USD and carried a nice list of standard features including the 4.6-liter Triton V8 engine, Billet grille, 6-disc CD Changer and MP3 compatible stereo and of course, plenty of Lobo badges and decals. 1,250 of these trucks were produced for the 2005 model year only.

Ford official press release:





Credit to fordf150.net for the image and information.

For 2005, Ford also introduced a new Texas-edition F-150 based on the XLT trim. I can't find what exact equipment it added other than the Texas-edition badges on the fender and tailgate under the F-150 badge.