shakes at highway speed

Several possibilities. It could be that road has regular bumps that excite a natural frequency in your suspension. Honda paid to have a road in Lancaster, CA grooved so that certain models played a song when driven over it at a certain speed. As fanofpetty said, the tires could make a difference.

Another is that your suspension and/or steering is too lose from worn bushings or ball joints. It could be OK on smooth pavement, but jiggers around when excited by bumps. Jack it up by the frame and tug on all the wheels to look for play and look for severely cracked rubber in the bushings.