With a 4" lift you will also need a SYE, or slip yoke eleiminator. If you don't know what It is, it basically helps reduce the rear drive shaft angle after a lift kit is installed. I know some lift kits come with them, so it might be something to look for. Without them you would get pretty bad vibrations. You will also need a new rear driveshaft when you get the SYE. This stuff might be like idk $450-$600??? Others will know more, the previous owner put all my parts on. Best of luck!