Factory HP exhaust manifolds

Been looking for just the left side-driver side-HP exhaust manifold for the SB motors. Headers warp around the steering center linkage and hang very low--speed bumps stink.

On E-bay there seems to be a big price diff. between the 72-73 manifolds-468's, compare to the 68-71 553's castings. To me looking at the pictures they look the same. I know the manifolds for the right side are much different for the later 72-73 but what about the left side. If I could care less what the casting # are, do the 553's flow any better than the 468's.