A differential is provided that includes a first and second side gear and a reaction block disposed between the first and second side gear. The differential further includes an engagement mechanism configured to have at least a portion of the engagement mechanism that is moveable from a retracted position to an extended position and a lock-out mechanism that is configured to engage the portion of the engagement mechanism. The lock-out mechanism is mounted to the reaction block. A reaction block for a differential in which a lock-out mechanism is mounted on the reaction block is also provided.