Private ["_lookPos","_vehicle"];

_vehicle = _this select 0;

// Lower gun/missile racks.
_lookPos = [(getPos _vehicle select 0) + (sin (getDir _vehicle))*20, 
(getPos _vehicle select 1) + (cos (getDir _vehicle))*20,
            (getPos _vehicle select 2) - 5];

(driver _vehicle) enableAI "MOVE";
(driver _vehicle) enableAI "TARGET";
(gunner _vehicle) lookAt _lookPos;