Our 1955-57 Chevy Belair Wilwood power brake booster kits mount in the factory location. These kits greatly increase your stopping performance while making it easier on the driver. This kit come with a Black Out adjustable prop valve taking all the quess work out of the installation. Also makes going to rear disc brakes a snap with out having to replace the existing prop valve found on most other kits. These components are a must when upgrading to disc brakes and come completely assembled, ready to install.