Hotchkis sells has a 4"/6" drop kit that uses just springs. They are well respected in the suspension market and claim the truck can be aligned with then 4" spring. You do have to run the drop shocks to make it work correctly. Like TopFuel1966 said, an adjustable trac arm, c-notch and adjustable trac arm are a good idea.
You probably can get by without the adjustable trac bar, until you are ready to purchase, if not at the same time.
http://www.azproperformance.com/Hotc...390-19392.html