Cain and Redline Manifold

[Innuendo]

That is the later style manifold, Cainy used to make them for Redline.

I think you'll find that the later ones were made by Terry Hardiman (Redline) for John Cain because Cain's original castings were atrocious hole riddled cast alloy and as you noted a different style and look.
This second style with Cain on it as actually a Redline casting badged up for John Cain. All Cain's original tunnel rams and manifolds now carry the Redline branding and superior casting.