I think the fourth (last) set are Hall’s - at least they matched the ones on my car, which were Hall’s.
My headers had the aluminized coating, the seams on the tubes, the collector welded after the seam, the very straight run of pipes into the collectors, and the three bolt muffler clamp....
On that set, you should check inside the collectors - mine were terrible.
On mine there’s was a ring from the flange sticking about an inch into the collectors, and the welds appeared as if they were done by a blind guy.
We cut the collectors off to get rid of that, and went to larger collectors with V-Band clamps.
PS.... I had heard that Hall’s header design came from boats (high performance ski boats, like Mastercraft, with the 351C).
Can anyone confirm or deny this?
@ Rocky, re: your P.S., I would be surprised if that were the case. I have a 94 Moomba (Pleasurecraft Marine/Ford) with a high-output 351W. AFAIK, the Ford inboards have been 351W, not 351C. Virtually all inboards have strikingly different wet exhaust manifolds that exit wet exhaust into rubber exhaust hoses out through the stern. A search of "Mastercraft/Ski Nautique Exhaust Manifolds" seems to corroborate this, can see pics there. There is a muffler of sorts behind there, as well.