They look like Blackjacks to me. Anyone remember Blackjack headers. They have the three separate flanges. I have a set of Hedman headers with the 1 3/4 primaries. Well made and worth the price. They were made with a 3/8th inch solid plate across the exhaust face of head. Never warped and the headers are 15 years old. Of course they are no longer available to my knowledge. Guess you have to go with what available now a days. Good luck.
