Radiators are not all made the same although they may say they are for your truck and will fit doesn't make them right for all purposes. I just replaced the radiator n my dually this past summer. A local shop ordered me one and when it came it was less fins per inch then the stock one I refused it and looked for another. I finally found one online that had the correct number of FPI. If I'm remembering correctly the difference was about 7,000 fins total. I experienced the less fins per inch problem back in the early 80's with a crew cab BBC I towed with. I needed a new radiator and had a shop put it in. I experienced rising temps just going up overpasses towing. Shop tried blaming the truck and tried finding something wrong and they couldn't. Finally one day the owner called and told me he'd found there were 2 different radiators available for my truck and that the other one had over 3,000 fins more for cooling. He purchased and installed the other one at no charge. Problem immediately disappeared
