I have a Brassworks in my '39. It has an 8ba so Lee at Brassworks customized one for my application. Very happy with it but it took a while and wasn't cheap. Other options are US Radiator, or Johnson's who took over Walker. Not sure if they make Brass or aluminum or both. One other option for aluminum is the Radiator Lady in SoCal. Never used her but I've heard good reviews.
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High-Quality Copper/Brass Radiators for Your Vehicle
The Brassworks; handcrafted radiators made in the USA