Have an 01' pre-runner with 252k. Within the last month or so, I have noticed a vibration at 65 mph +/-. It runs smooth at 60 and smooth at 70, but in between, a little rough. I have the tires balanced, but no change. Any thoughts.....ball joints perhaps? I basically drive the highways all day for work, and put a fair amount of mileage on each week. Would like to get this corrected, cause I don't like driving under the speed limit to keep the vibration down.