I have a 68 Z28, Canadian car, it has a KD1 option (Less Air Injection Reactor for GM of Canada) on GM Restoration paperwork. A friend of mine did alot of research on Smog Equipment on Canadian cars, he was told the Cdn cars had the same manifolds as the cars with Smog Equipment but the holes for the tubes had factory installed plugs. The car presently has Hooker headers installed & I am looking to replace them with stock manifolds but want to get right ones. Thanks lorne