It seems that all newer heatercore products are brass instead of copper.... Are there any that are still being made with copper; the large fedco seems to be brass now. Also, whats the difference between Autozones' fedco and Napa's Balkamp, they are the same sizes but balkamps are black and look like they are ALUMINUN?? What are performance differences between a brass and copper HC of same design, and will brass cause corrosion like aluminum?