That is true, there is a spring rate difference between the v6 and v8 springs. It is not advised to use the wrong springs since it will affect your handling, load capacity, towing, tires rubbing, suspension travel, braking and also if you have a good size system in your vehicle, you will notice it will not look properly lowered from the outside. See, if you can exchange them or return them and be able to to get the correct springs for your suv