The only time the load leaf comes into play is when you are carrying a very heavy load such as trailering, then it prevents the springs from becoming completely flat. I don't think with the add aleafs you will be able to flatten the leaf pack enough to have the ends of the load leaf contact the pack if you do not exceed the Xterra's weight capacity or towing capacity. You do not need to remove the springs from the truck to install a new centerpin, once the pack is released from the u-bolts you can then place a floor jack under the diff and raise the diff enough to insert a new centerpin.