Bilsteins are a great shock to go with, and they offer two options. The 4600, HD Blue Yellow shocks are a great stock replacement and will really improve the ride.
The 5100s, silver and black shock are just a bit more, but have the added feature of an adjustable spring seat with 3 height levels, allowing for up to 2.5" lift in the front, which will give the truck a nice, level stance. They are also zinc coated for corrosion resistance.