I use the 6901s on my 71 5.0L. However i had to have part of one of the tubes cut and re-routed slightly because my pitman arm (i think thats what it's called?). other than that they have fit nicely. They also gave me enough clearance to drop my transmission without unbolting the headers. great for the price. May need slight modifications but some have had perfect clearance. My 5.0 did seem to sit a little farther back than normal. edit: also my car was a column shift C4
finally got a few pics of the exhaust port size of my 6901's compared to the Fel-Pro 1486, I will have to build up the bottom of the exhaust port so that it will seal against my AR aluminum heads and/or vertically enlongate the flange mounting holes, so that 6901's are more centered with the exhaust ports. David