I have a '64 C10 that originally had a 292 6 cyln. I converted the truck to a '97 Z71 chassis with a 5.7 Vortec V8 and a 4L60 trans and a GM 10 bolt w/373 gear ratio. I used a cross-flow Speedway Racing aluminum radiator with a custom fabricated shroud.. I had a '65 C20 that I had for 18 years. It was a V8 AT w/AC.. The original cooling system was very marginal, tried everything to keep the truck from overheating during summer driving in desert/mountainous areas. Never had that problem with later model vehicles w/ cross-flow radiators. Wm