Your year model code is found on the bottom right hand corner of your serial number decal. It will be a single letter as per the diagram below which can then be matched to the chart. Note: The letters will repeat in the below chart so use your judgement as to the correct year, ie: the engine in the picture is a 2003 model and not a 1982 model. From 2019 and onwards there is no letter code for the year. Under the cowl on the powerhead there will be a sticker a bit under 1 inch square with the year of manufacturer on it. 

MUST READ - the sticker on the left is a 115hp 2 stroke engine. The sticker on the right is a post 2019 model 90hp 4 stroke engine. The F designates 4 stroke. Yamaha service kits for 4 stroke engines also work off the model code. The model code for this 90hp is the LB part. L represent Long Shaft but its the B that's important. The 6FP part is NOT important. MAKE SURE YOU KNOW WHAT YOUR MODEL CODE IS WHEN SELECTING A SERVICE KIT.

1973 1974 1975 1976 1977 1978 1979 1980 1981 1982
Z Y X W V U T S R Q
                   
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
P L K J H G F D C B
                   
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
A Z Y X W V U T S R
                   
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Q P N K J H G F D C
                   
2013 2014 2015  2016   2017 2018         
B A Z Y X W