Vehicle Compatibility?Compatible with Buick Rainier 2004–2005, Compatible with Chevrolet SSR 2003–2006, Compatible with Chevrolet Trailblazer / Trailblazer EXT 2002–2005, Compatible with GMC Envoy / Envoy XL 2002–2005, Isuzu Ascender 2003–2005, Oldsmobile Bravada 2002–2004, and Saab 9-7X 2005. OEM Replacement Numbers?54-74821, 5474821, DL178670, 18047694, SK5474821.Fully interchangeable with the original factory part. Please confirm your OEM number or vehicle configuration before purchasing. Restore Braking Performance?Effectively restores vacuum pressure and braking assist function. Provides stable braking force, reduced pedal effort, and a smooth, consistent braking response in all driving conditions. Easy Installation?Designed as a direct-fit replacement for the factory unit — no modification or special tools required. Connects directly to the existing master cylinder and vacuum hose for quick and clean installation. Durable Construction?Built with reinforced steel housing and high-quality diaphragm materials to resist corrosion, deformation, and leakage. Each unit is individually tested to ensure long-lasting and reliable performance.