Al, I just put them on when I installed my engine and they fit good. They wont go on without raising the engine up an inch or two and they hug the floor board nice and tight. The bolt pattern where the collector bolts onto sits about 1/4 inch from the floor board. I have the round ports Doug's and auto trans and these headers do not contact anything but it is tight around the steering gear box. No banging and beating to make them fit.