I may be just a shade tree mechanic, but It does seem a bit premature though. Honestly, I would clean off the corrosion with a paste of baking soda and water. Then, I would make sure it's good and drying before I put on some Dielectric grease. If the battery tests well, there's no real point in replacing it, if it is the metal going on to the battery terminal post that is causing the corrosion.
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