Add-a-leafs can be the ticket when only 1-2" of lift is desired. You may want to consider front leafs to level the vehicle or to cure the sag caused by a winch or snow plow. Rear add-a-leafs are also frequently used to beef-up the rear springs.
Remember that spring fatigue is common among older vehicles and ones that have been used frequently for heavy hauling or towing. All kits include (2) single leafs and (2) new tie-bolts & nuts. SUPERLIFT Add-a-leafs are designed to be used with stock leaf springs, not aftermarket springs with additional leafs or higher arch.