Or----(there's always an "or")---you can do it like Lokar does. There shifter will only move back and forth---no sideways movement at all. Instead of their lockout plate with slots being arranged to one side of the shift lever, it sets directly in line with the lever. There is a spring loaded sprag (which is just good old engineering talk for a peice of metal that engages the teeth on a gear to prevent it from rotating) fitted into the lower part of the Lokar lever. This "sprag" is kept in contact with the "teeth" on the lockout gate, so that the shift lever can not be moved. When you push down the button in the top of a Lokar shifter, this in turn pushes a flexible peice of cable, (Lokar shifters are actually hollow centered like a tube). The other end of this flexible cable retracts the sprag from contact with the teeth on the lockout plate, and allows the shifter to move.---Simple, Huh???