Here's THE NO. 1 site on oil and related matters -- I highly recommend it:
In a nutshell, any of the more common, well known, synthetic oils will work in your truck. Some people favor one or the other for various reasons. One is cost. Another is how long you can run the oil between oil changes. Another is the additive package in a particular oil. Mobil 1 has been used for up to 10,000 mi. with a lab test thereafter which showed that the oil was still doing its job. Mobil 1 EP (Extended Protection) will go even longer. The word on Pennzoil synthetic is that its good for up to 7,000 mi. I personally don't like Amsoil syn oil because of their marketing process, but its also been tested at up to 10,000 mi. The others are good for up to around 7,000 miles, so long as they're fully synthetic, not a synthetic/conventional oil blend. For you, I'd recommend Pennzoil, run for up to 7,000 mi., or Mobil 1, run for up to 10,000 mi.
For an oil filter, I recommend either a Purolator Pure One, a WIX, or a NAPA Gold (which is made by WIX), and you can run it 10,000 mi.