Shakes at 60 mphexplorer xlt

Tires would be the 1st place to check. If you seem to feel it more in your legs then it is likely the front, if felt more in seat bottom then could be a rear tire. Depending on how severe the vibration is there could be a tire developing a tread seperation and should be checked right away. A simple balance of the tire and wheel assemblies may be all that required also but when on a balancer they should be able to tell if the tire has a more severe problem.
Driveline components could cause vibrations also however if the above sounds like it fits then check that 1st.