An aluminum radiator is likely to have crimped on plastic tanks and is not repairable. I think my '41 has copper fins on brass tubes soldered to brass tanks. Over the long haul I would choose brass if I wanted an original look and toughness and repairability. I don't think there is a significant difference in the thermal transfer ability of brass and aluminum. The thing to check also,is the thickness of the core. i.e. the number of rows of tubes.
