The distance of the race in which Northerly raced in group G3 was 2400 m.
[['[TABLECONTEXT]', '[TITLE]', 'Northerly race record, 2002-03 Season as a Six Year Old'], ['Manion Cup', 'DISTANCE', '2400 m'], ['Manion Cup', 'GROUP', 'G3'], ['[TABLECONTEXT]', 'RACE', 'Manion Cup']]