Interesting.
When I upgraded my 318 with a 4bbl, although my Scamp already had a dual exhaust, it was small diameter and quite old (installed in the early ‘90’s), so I replaced it with a 2.5” exhaust with the 71+ 340/360 exhaust manifolds. The 318 manifolds I had removed looked exactly like the pair you recent found Tanker (passenger side one had the ribs on it).
