Paging Jim Rhinehart (Rhinodart)

I would say it was engineered by the factory as other parts were.
Old thread however I just stumbled upon it so anyway.. Born a buckeye and bleeding scarlet & gray, I know the answer to your question quite well. Credit for the left side big block A-body exhaust manifold (originally designed in '66) BELONGS to drag racing GodFather, Arlen Vanke, from Akron Ohio. R.I.P. "Akron Arlen"