Can anyone tell me the vintage of these Shimano 600 ams? I imagine they must be late 70's from the design, but I don't know, so I'm asking the great mind of VBMX.

Thanks, Frazer

Date code on the back of the arm

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 1994
T 1995
U 1996
V 1997
W 1998
X 1999
Y 2000
Z 2001
A 2002
B 2003

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

cheers reilley1,
is that the same code as for the hubs and all shimano gear?

yes

Fred Fredburger sure does know a lot of stuff about stuff. Thanks Fred Fredburger!

One arm is March 79, the other is Aug 81, as it turns out.