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Do you see evidence of corrosion inside the radiator or does the coolant drain out nasty looking when they fail? Maybe it’s a vibration/fatigue failure. Maybe try an isolator between the four mounting screws and the radiator support to prevent vibration from migrating to the radiator. Most modern cars with aluminum radiators have rubber idolaters where they mount.
Not vibration per the analysis provided. Electrolysis enjoys environments where dissimilar metals exist or electric current travels. This is why aluminum boats have isolated ground and are not chassis grounded.