I need to replace both the rocker and corner on my truck cab. The concern is, because the rearmost part of the rocker inner and outer (at the cab corner) is completely shot as is the corner, I'm concerned that fit up of these parts may be difficult. How can I be sure these parts go back on properly? Do I need the door on to check these parts? (doors are off and the cab is on a rotisserie) Part of the floor will have to be repaired along the top of the rocker seam. Should I fab this part 1st to help aligning the other parts? Any advice?