A lawful agreement by either the seller or the buyer for exclusive dealing in the kind of goods concerned imposes unless otherwise agreed an obligation by the seller to use best efforts to supply the goods and by the buyer to use best efforts to promote their sale." Id. Official Comment 5 to U.C.C. section 2-306 makes no
distinction between "best efforts" and "reasonable effort and due diligence." Not all courts agree.
10. See, e.g., U.C.C. § 2-306(2), supra note 8. Others, however, are immutable, like the "implied" covenant of good faith. See U.C.C. § 1-102(3). The Code speaks of good faith as an "obligation," prescribed by the Code, rather than an implied term, but traditionally it has been called an implied term of the contract.