thus appears almost as a harbinger of Chevron. Under Chevron, “if the intent of Congress is clear,” the court “must give effect to the unambiguously expressed intent of Congress.” Chevron, 467 U.S. at 842-43, 104 S.Ct. at 2781. If “Congress has not directly addressed the precise question at issue,” and the agency has acted pursuant to an express or implied delegation of authority, the agency’s statutory interpretation is entitled to deference, as long as it is reasonable. Id. at 843-44, 104 S.Ct. at 2782. Although an agency manual often may not purport to carry the force of law, see Christensen v. Harris County, 529 U.S. 576, 587, 120 S.Ct. 1655, 1662-63, 146 L.Ed.2d 621 (2000); United States v. Mead Corp., 533 U.S. 218, 226-27, 121 S.Ct. 2164, 2170-71, 150 L.Ed.2d 292 (2001) (<HOLDING>), the Postal Service’s disputed regulations in
holding that chevron deference is due only to a reasonable interpretation made by the administrator of an agency holding that agency action is final  and thus has legal effect  only if taken by officials possessing properly delegated authority holding that administrative implementation of a particular statutory provision qualifies for chevron deference when it appears that congress delegated authority to the agency generally to make rules carrying the force of law and that the agency interpretation claiming deference was promulgated in the exercise of that authority holding that a longstanding agency interpretation was no longer entitled to chevron deference given that the agency had changed its position on the issue holding that chevron deference is due only when the agency acts pursuant to delegated authority and the agency action has the force of law