It's important that the liner has a surface to "bite" into once it's applied. Using wet/dry 36-grit sandpaper, we went to work sanding the entire bed of the El Camino. Note: employing some friends for the day can surely expedite the process. We teamed up with Michael Consolo and attacked every possible edge and crevice. This included the back of the cab, the sides, the floor, and every corner.