I have a set of the GT40 X302 heads. I have had some problems finding headers to fit these heads. The problem is the width of the GT40's port on the exhaust side. Most headers I have looked at are narrower than the head opening, some are further restricted by the weld on the inside of the opening. I did find a set of headers that came close to being the right size off a 95 S351 supercharged Saleen Mustang. Only, these are damaged and I don't know if I can find the parts to repair them. These were made by hooker for Saleen but are no longer available or I would try to buy a new set. I need shorty style as I am putting the engine in a 64 F100 and it's hard enough to find some shorties to work. I bought a set of stock lightning headers, but those had such small openings that I decided not to use those. I've bought several sets of headers to try, mostly used, but still have not found the any that I am satisfied with on the exhaust fit. EXhaust ports are aproximately 1 3/16 inche wide and most of the headers I've found are restricted on width, although the real limiting factor is the placement of the mounting bolts. Hopefully, one of you lightning owners have solved this problem and can help me out with some recommendations.