US radiator all the way, yes they are expensive, but it is an American company, and will last forever. A brass radiator actually rejects heat better than aluminum, there are several reasons manufacturers use aluminum, it is cheaper, lighter, and will withstand pressure better. But in this application, a brass radiator would be the best choice, as the weight savings will have little or no effect on the horrid fuel consumption these trucks have, and as most of them have either no pressure or very little, that isn't usually a concern either. The cost however might scare some away. As a side note, they will polish the top tank to a mirror shine for $50, and they take special care to make really pretty solder lines on the polished units.
