A cutterbar lockout tool, a header including such tool and a method for locking and unlocking a cutterbar assembly using such tool are provided. The lockout tool includes an engaging portion for engaging a down-stop linkage assembly of the cutterbar assembly and an elongated body extending from the engaging portion. The tool is used to apply torque to the down-stop linkage assembly at a significant mechanical advantage in order to reposition the cutterbar assembly whereby the cutterbar assembly may be easily locked and unlocked relative to a header chassis.
