2001 Mercury Mariner 50-60HP Factory Service Manual, Page 269Get this manual
CYLINDER BLOCKCRANKCASE
Cylinder Block Reassembly
Selecting New Main Bearings
1Locate the main bearing code letters on the cylinder block2Refer to the following reference chart to select the correct main bearings3Use the color coded main bearings that match the main bearing code letterMain Bearing Code Letter Main Bearing Color Code Blue Black Brown