One of the weakest points of a pickup truck is the lower rear corner of the cab. It is always the first place to rust out, because the vehicle is exposed to water and road salt at that particular location. To complicate matters, the factory drain holes often plug with dirt, allowing those corrosive elements to accumulate and rust the metal away. Fortunately, you do not have to be trained body man to fix a rusted cab corner.
Hold the patch panel, which is slightly thicker than the original sheet metal on the body and shaped like the corner of the cab, against the vehicle and outline the patch panel with a permanent marker.
Remove all the damaged metal and as much of the other metal as possible within the outline of the replacement corner by cutting it with a Dremel tool, or something comparable, that has an abrasive wheel mounted to it. Leave enough of the original metal on the sides and front of the cab corner to epoxy the patch panel to the cab.
Remove all the paint from the corner in the area where the patch panel will go by sanding it off with sandpaper. Rough up the glue areas with a very rough grit sandpaper, on both the vehicle and inside the patch panel. Clean all sanding dust off the vehicle and the inside of the patch panel.
Mix a batch of epoxy large enough to cover all the glue areas on the patch panel and cab corner. Spread the epoxy on the roughed-up areas of the vehicle and the roughed-up edges of the patch panel with a Popsicle stick. Fit the patch panel to the vehicle.
Slide a 2-by-4-inch block of wood between the cab and the truck bed at the top and bottom of the patch panel. Hold them in place by wedging a wooden trim wedge between the patch panel and the truck bed.
Hold the bottom of the patch panel to the bottom of the truck body by placing a pair of vise grips at either end of the bottom of the patch panel where the panel and body meet. Clamp them together. Wipe off any epoxy that squeezes out of the seams between the patch and vehicle body. Allow the epoxy to set up for 24 to 48 hours.
Cover the seams on the front and back of the panel patch with auto body caulk. Cover the seams that are always visible with body filler. Allow the body filler time to dry, and feather the dried body filler in the seam with sandpaper so that the patch and vehicle's body look as if they are one, completing the repair of the cab corner.
