Shakes when I hit the brakes?

Hello,

Just to clarify, it only shakes when you apply the brake at highway speed, and no other time?
You could have a worn lower ball joint or lower control arm bushing.

https://www.2carpros.com/articles/how-to-release-a-ball-joint
https://www.2carpros.com/articles/lower-control-arm-bushing-replacement

It could also do that if you have a out of balance tires.

I have attached the control arm and ball joint replacement procedure for your reference. Also included on how to check for worn out ball joints and control arms.

Please let me know of any questions.

Thank you.