1968 or up Round Port Ram Air Exhaust Manifolds.
 

I am looking for a set of new or used Round Port Ram Air Exhaust Manifolds that can bolt up to the Edelbrock Round Port Cylinder Heads. AMES has discontinued the item with 2 1/4" collectors and now only offers the 2.5" collectors. If you order the 2.5 inch it looks like they are back ordered, so not sure if they will actually deliver them.