i have a 2000 ranger xlt 4wd and recently i was on the toll road and a horrible shaking and bouncing happend got home and cant figure out what it us it feels like somone jumping on my rear bumper when i go past 60 and i cant find out why. please help its my only veichle and need it to get to work any suggestions help

 

Bad tire, un-balanced wheel, Try rotating the tire front to back and see if the "bouncing" move to the front.