Our 1947-53 Chevy and GMC truck Wilwood power brake booster kits mount on the firewall. These kits greatly increase your stopping performance while making it easier on the driver. This kit come 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 haveing to replace the existing disc/drum prop valve found on most other kits.These components are a must when upgrading to disc brakes and come completely assembled, ready to install.