They can make aluminum flues wider (ex; 1 1/4" vs 3/4" on copper) giving much more flat side area to attach cooling fins. There is a taper at each end of any tube that is not cooling much because of no fin attachment.
Aluminum radiators don't cool as well as copper/brass and they don't look right on an early V8 unless they are painted. Go with a Walker! it will be the last one you ever buy!
you can buy 3 superoir radiators for the price of one walker i have two walkers and three superoirs cant see any dif. all new cars have aluminum. make shur its USA made what ever you buy