There should be 3 tall ones, 2 short ones, and the rear cross sill that goes under the tailgate. The 2 of the tall ones go at the front part of the bed at the bed mounting points, the other tall one goes at the position just before the rear sill. The 2 short ones are just supports, and go over the "hump" on the fram where the axle sits, one ahead of the axle, the other after the axle.