The U-joint has a pair of locking set screws on the shaft side. Note also the splined end of the steering column protruding slightly through the end of the U-joint. Always make sure you do this, though also ensure it clears the actual joint and allows it to move to its full travel, even if you're not using it at a great angle. Why? Because I know of one person who had the set screws come loose and the shaft drop out of the U-joint while driving!