While maneuvering in parking lot car would not shift from Reverse to Drive after backing out of parking place, error on dash stated shift module failure. Tow truck driver manually engaged shifter to drive, too car to Freeman Ford. Upon inspection shifter grommet at transmission had worn not allowing car to change gears, $4 in parts, $300 in labor to fix. Fortunately the car was just blocking a post office parking lot, if this had been a maneuver in an intersection it could have caused an accident. There was no indication this failure was going to occur.