Before aluminum radiators were around, the only upgrade from a factory 3-row radiator was either a 3-row high efficiency model or a 4-row. A 4-row added another row of cooling tubes which provided approximately an extra 20% of cooling power over a 3-row. Back 30 years ago, you could roll down to your corner radiator shop and even have him ‘recore’ your factory radiator with an upgraded 4-row core.