Our 1973-87 Chevy and GMC truck 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 comes with a Black Outadjustable 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.