OER Parts offers a selection of OE Style Manifolds for your 1968 Pontiac GTO. OER Parts offers 1968 Pontiac GTO Exhaust Manifolds without Smog Tube Holes, 1968 Pontiac GTO Exhaust Manifolds with Smog Tube Holes, 1968 Pontiac GTO Hemi Exhaust Manifolds, 1968 Pontiac GTO Ram Horn Exhaust Manifold, 1968 Pontiac GTO Ram Air I Exhaust Manifolds, 1968 Pontiac GTO Ram Air II Exhaust Manifolds, 1968 Pontiac GTO Ram Air III Exhaust Manifolds, and 1968 Pontiac GTO Ram Air I Longbranch Exhaust Manifold.