Ok ladies and gentlemen My 72 duster is the car they designed the headers around. There built for 318 340 or 360 with STOCK cylinder heads and No power steering.. the car has a stock 4spd with a scatter shield so there is plenty of room for automatics. My 340 has 11.1 comp. fully ported j heads big hydrolic flat tappet cam strip dominator and a reworked 750 Holley. I had old 1 7/8 hooker race headers on it for A and E bodies that they discontinued along time ago. I will say this, these headers blow away all those other headers and I had them all! You can install and remove them with the engine in the car! That alone is worth it to me. They changed the whole tone of the engine the car has a lot more low end torque and it pulls harder going through the gears the merge collectors actually work I will post some pics within a few weeks when I have time off underneath the car from both sides.