i have a vibration from 55 to 70 mph.

Hello, Usually 55-70 mph vibration is caused by a wheel or wheels that are out of balancing and need checked for balancing. A faulty tire usually vibrates at low speeds as well as bent rims. Lastly, a drive axle concern can cause vibration. Take the vehicle to a shop that has appropriate equipment for wheel balancing first -- they can troubleshoot from there.