A brand-new larger power brake booster for the Opel GT! Provides a modern brake pedal response, for a substantially lower cost than rebuilding your original. No Core Fee or Exchange required. Best when paired with #4013 or #4013-22 Master Cylinder (save $50 when ordered as part #combo). Incorporates built-in check valve into inlet fitting. Also installs using an original-style vacuum hose (part #4041). Note: WILL NOT FIT Manta, Ascona or Kadett.