Ford 2003 Mustang Workshop Manual page 1809

53. Apply silicone gasket and sealant to the woodruff key on the crankshaft pulley.
54. Using the special tool, install the crankshaft pulley.
55. Install the crankshaft pulley and tighten the bolt in four stages.
Stage 1: tighten to 90 Nm (66 lb-ft).
Stage 2: loosen the bolt one full turn.
Stage 3: tighten to 50 Nm (37 lb-ft).
Stage 4: tighten an additional 90 degrees.