To service the extension housing seal of the 42RE automatic transmission, first, lift the vehicle and mark the propeller shaft and axle yoke or companion flange for reference. Disconnect and remove propeller shaft, then using Seal Remover C-3985-B remove old seal from overdrive extension housing. For installation, position the new seal on the overdrive housing and use Seal Installer C-3995-A to drive it into place. Gently insert the propeller shaft slip yoke into the housing and onto the output shaft splines, aligning the marks made on the drive shaft during removal, and connect the propeller shaft to the rear axle pinion yoke.