I have a 67 XR7. confused as to what year springs are interchangeable? Some sites show 67-73 springs are all interchangeable (aware engine specs can impact). Other site show leaf springs for 70-73 are interchange able only. What is the right answer?
The springs are specific by year and engine options and other options (like PS and AC). The factory IPC gives data on what parts were available over the counter. While the length might be the same 1967 - 73 the weight of the car and the springs are not. Many many variables exist.
Physically the springs will interchange but, as Royce noted, different front and rear springs were installed depending on what options were installed (extra weight).
The stock Cougar springs were very soft - for a comfortable ride.The springs for the GT were much stiffer. Are your trying to duplicate the original handling characteristics or improve them?