it depends on the truck, not the rack. on the edge, the rack is mounted up higher inside the frame whereas on the XLT it's mounted in front of the frame down lower towards the lower control arm. because of that, where the tie rod mounts to the spindle/upright (the OUTER tie rod end) is in a different spot between the two. this is only for 2wd trucks, the 4wd all mount the rack in the same spot as the 2wd edge.
if he were to swap to a 4wd spindle, he would get some funky steering angles that can result in the truck being hard to align or have bad driving characteristics like wandering while it's driving, or having bump steer (tires move in or out and try to steer the truck every time he hits a bump)