I guess it's a cost thing. Back in the 70's when I had a 1970 Beetle, heater boxes were very expensive. Over $200 each (and that's in 70's dollars). Now, heater boxes are about half that. So, you can imagine what 'real' aluminum cored heater boxes would cost today? The market is probably too small, especially for the larger boxes. And low volume usually means higher costs. The main problem is recoring the old aluminum cores. 1 3/8 " pipe in the center, surrounded by aluminum and the opening is square at one end. Maybe someday someone will start making new, larger diameter aluminum cores. I may still try to build a set of aluminum cored 1 5/8 " heater boxes. I may try the header wrap on my boxes.
(Message Edited 2/9/2003 6:05:22 PM)