truck shakes at 70 to 74 miles an hour. any ideas on how to fix problem? i have a 2 wheel drive f150 with 275/60/15 hankook ventus h101. i've replaced u-joints, center bearing carrier, had tires balanced 3 times by 3 different tire shops. i have 110,500 miles, 5.8 liter, auto, truck shakes loaded or unloaded.

 

Inspect the drag link, the tie rods, and the ball joints.