Ford 2003 Mustang Workshop Manual page 1794

NOTE: Before assembling the cylinder block, all sealing surfaces must be free from chips, dirt, paint
and foreign material. Also, make sure the coolant and oil passages are clear.
5. Install the upper main bearings into the cylinder block and the lower main bearing into the
crankshaft main bearing caps. Lubricate the main bearings with clean engine oil.
6. Install the crankshaft into the cylinder block.
7. CAUTION: Make sure the coated side of the thrust washer with the 5-mm wide oil
grooves faces the crankshaft thrust surface.
Push the crankshaft rearward and install the crankshaft thrust washer at the back of the No. 5
main boss.