OMC OEM GEAR HOUSING ASSY., 21:17, 5.0 L. NOT SHOWN (INDENTED PART NAMES INDICATE CONTENTS OF PRECEDING ASSEMBLIES) USE 21:18 GEAR RATIO FOR 5.0 LITRE MODELS CONVERTED TO RUN AT HIGH ALTITUDE (ABOVE 5000 FT./1524M) - 0983887 | boats.net