The NADA web-site has a fairly nice listing of the model numbers.
(National Automotive Dealer Assn.)
http://www.nadaguides.com There is a letter inserted in the "Savage" model numbers to indicate Pull-back (P) or flat (F or L). There is a K inserted in the 2001 and later models.
Adding to Verlagen's Year list:
1986 = G .... LS650FG/PG SAVAGE
1987 = H .... LS650LH/PH SAVAGE
1988 = J .... LS650PG SAVAGE
1989 = K .... not offered in USA
1990 = L .... not offered in USA
1991 = M .... not offered in USA
1992 = N .... not offered in USA
1993 = P .... not offered in USA
1994 = R .... not offered in USA
1995 = S .... LS650PS SAVAGE
1996 = T .... LS650PT SAVAGE
1997 = V .... LS650PV SAVAGE
1998 = W .... LS650W SAVAGE (Not sure why there's no P, possible omission at NADA site)
1999 = X .... LS650PX SAVAGE
2000 = Y .... LS650PY SAVAGE
2001 = 1 .... LS650PK1 SAVAGE
2002 = 2 .... LS650PK2 SAVAGE
2003 = 3 .... LS650PK3 SAVAGE
2004 = 4 .... LS650PK4 SAVAGE
2005 = 5 .... S40 BOULEVARD (Not sure why there's no K5)
2006 = 6 .... S40K6 BOULEVARD
2007 = 7 .... S40K7 BOULEVARD
2008 = 8 .... S40K8 BOULEVARD
2009 = 9 Got to wait.... have patience....
2010 = A Got to wait.... have patience....