This is strictly an FYI since Doug's Headers tech didn't have an answer. I mocked up a WC T5 in my 66 coupe running Doug's header part # D690YA. These headers are designated automatic C4 only on the tech page. Threw the T5 in, the clutch fork has plenty of movement and clears the collector pipe. Running a 86 5.0 bell housing, only had to remove a slight bit of material on the upper outer corner where the factory clutch cable mounts to clear the header down pipe. Hope this helps....happy christmas!