Custom Van third brake lamp when opened, will be corroded at the bulb fixture area. The best thing to do is to replace it with the new LED style Third Bake lamp from East Coast Auto Toys. The only tools needed for this job a screwdriver and your typical wire tools to connect your two existing wires with new butt connectors. The unit pictured below is guaranteed for five years against failure and lifetime against corrosion under normal conditions
Third Brake Lamp fitting most Chevrolet Astro Vans
Custom Van Third Brake Lamp Replacements
Third Brake Lamp fitting most Chevrolet Astro Vans