REQUIRED For Replacement labeled Engines, Long Blocks, and short blocks sold within the U.S. and U.S. Territories the engine core (i.e. old engine) that is removed MUST be returned to your selling Caterpillar dealer, so that they can return to Caterpillar  OR  destroy, as required by law. Proof of return or destruction will then be provided to the EPA and or California ARB if required. See PELJ1301 for additional details.