The very first thing to consider is, What is the trucks purpose. The second is thing to consider is what weight laden modifications do you have or intend to make (i.e. bull bar, winch, trail armor).
For Example: I have a '99 4runner with the purpose of being a DD, and to hall the family our to the desert to explore/camp. Light to moderate 4 wheeling.
I planned for a bull bar, winch w/synth rope, sliders and 75lbs of skids, plus up to 400lbs of gear or pull my trailer.
Then I called ARB and they helped me decide which coils and shocks would best suit my needs, and I am very happy with what I have so far.
"Adventure is a word that get's over used, to me real adventure doesn't start until it all goes wrong"- Yvon Chouinard