The guy at this thread... http://www.hotrodders.com/forum/appliance-headers-first-gen-camaro-156947.html
says he has Appliance headers and they look basically like yours. However, he bought them as used items in a
junkyard and he may not necessarily be right. Below are two photos of his headers and they match up well with
yours. I think his are actually BlackJack headers with the optional "Alumacoat" and yours may be the standard
BlackJack headers without the special coating. I don't have a lot of '70s magazines but I will keep looking
around to see what else I can turn up.
Here is a Summit Racing Equipment ad for BlackJack headers from December 1981. The front tube (#2) is not
routed quite the same as yours but since it is a drawing, it may be just drawn incorrectly. The tiny color ad below
that shows the driver's side Alumacoat BlackJack header and that seems to be a match.