Ford 2003 Mustang Workshop Manual page 1324

50. Make sure that the copper (marked) chain links are lined up with the dots on the crankshaft
sprockets and the camshaft sprocket.
51. NOTE: Sensor ring teeth must face forward.
Position the crankshaft sensor ring on the crankshaft.
52. NOTE: The front cover must be installed within four minutes of applying sealant.
Apply silicone gasket and sealant in the locations shown.