this info is from Rick AKA Reilley 1.
Ok, this is for the purist who wants to know the date of manufacture of their Shimano components. The first letter is the year, the second one is the month:
YEAR
A 1976 B 1977 C 1978 D 1979 E 1980 F 1981
G 1982 H 1983 I 1984 J 1985 K 1986 L 1987
M 1988 N 1989 O 1990 P 1991 Q 1992 R 1993
S 1994T 1995 U 1996V 1997 W 1998X 1999 Y 2000 Z 2001 A 2002 B 2003 C 2004
MONTH
A JAN B FEB C MAR D APR E MAY F JUN G JUL
H AUG I SEP J OCT K NOV L DEC
so now ye know how old ye shimano bit and pieces are.