2003 Ford Excursion Telescopic mirror with signal light.

The telescoping side mirrors will mount on if you got it for the correct model ,year . Does your original side mirror have a signal light? If not then you may have to run the wiring yourself for the signals and tie it into the turn signal switch wiring on the steering column. If it is the power telescoping mirror then it would not work, because your power mirror switch does not have a switch to operate that adjustment. You could go with the manual telescopic mirror with signal light though..