1989 Jeep Cherokee SHAKES AT HIGHER SPEED

MY 89 JEEP WAS RECENTLY PURCHASED, RUNS FINE IN TOWN BUT WHEN I GET IT AT HIGHWAY SPEED AT 50 OR HIGHER IT OCCASSIONALLY SHAKES, NOT LIKE A CONSTANT SHAKING WHEN A VECHICLE NEEDS LINED UP BUT AN EXTREME SHAKING ALMOST LIKE U THREW THE BRAKES ON AND IT IS HOPPING, IT IS A VERY SCARY EXPERIENCE, WHEN YOU SLOW DOWN TO PULL OFF ROAD IT STOPES BUT THEN AFTER U PICK UP SPEED AGAIN IT STARTS AGAIN. IT ACTUALLY FEELS LIKE ALL THE TIRES ARE COMMING OFF. I WAS TOLD A WHEEL BEARING NEEDS REPLACED COULD THIS BE THE PROBLEM? COULD THT CAUSE SOME KIND OF A LOCKUP?