Category: DIY & Crafts, Home, Repair Services

The factory foam gasket on the 2000 Sierra is the root of the problem. To ensure you never deal with a wet back wall again, do not rely on the thin foam that comes with many replacement lights. Instead, purchase a sheet of closed-cell foam rubber or silicone rubber (1/4 inch thick). Trace the outline of the new light housing onto this sheet and cut a custom gasket. Alternatively, apply a bead of high-quality outdoor RTV silicone (like GE Silicone II) to the mating surface. Allow the silicone to skin over for a few minutes before tightening the light down. This creates a watertight barrier that will outlast the truck.