More exhaust manifolds
I should add that before '74, the 360 was never labeled as "HP" and never had more than a 2BBL.
In '74, the HP 360 was available in A/E/B-Bodies with a 4BBL and bigger cam, but (as far as I know) only the A-Body got the DS "340" manifold (the casting numbers even match).
After '74, the 360 was available, but I am not clear on if it was an HP or even if it had a 4BBL, so no idea what manifolds it had.
Later when the E58 360 was released in Volare's, LRE's and such, it was considered an HP, but I don't believe it would have come with large outlet manifolds. Even if they were they, wouldn't have been the same shape as the DS "340" manifold in question here.
So, when TF360 asked "Do you know if factory 1974 360 hp mainifolds ( a-body) have the 2 1/4 outlet on the drivers side" he was asking about the "340" manifold.