It is so worth the money to go with Alcan if you are planing on keeping your truck. You weigh your truck and then take a few measurements and they are helpful at that stage. I couldnt believe how sweet of a ride my Alcans were over running Toyota rears up front. i did that for a couple years and with a 4.3, if you dont get the right spings it will dip way too hard when your are on the trail