DO NOT buy the cheap junk uniball control arms from Amazon or Ebay. Search around for the failure rate on them and what happens when they fail and they will. Replacement arms are not just for guys that wheel, they make a huge difference on road also. An incorrect alignment is no fun on the road, trust me, I know. at 3" and 1* of caster, it sucks, Going back to 4* makes a huge difference in ride quality and handling.
http://www.toyota-4runner.org/5th-gen-t4rs/227005-ebay-uniball-ucas-warning-w-pics.html
yes it's a pretty critical part... I love my Total Chaos UCA's!