I am trying to find out what year this marlin 39a was manufactured. I have checked the web site
http://oldguns.net/sn_php/marlinlookup.php

But is comes back with nothing

The serial number is S16XXX

Last year I just called Marlin and gave them the serial #'s of my Marlins, one of them was a 39A also. Maybe they can help.

Steve E......

S prefix was probably manufactured in 1959 or thereabouts.

+1
58 or 59.

The manufacturing dates for marlin are:
C=1946
D= 47
E= 48
F= 49
G= 50
H= 51
I= none made
J= 52
K= 53
L= 54
M= 55
N= 56
O= NONE MADE
P= 57
Q= NONE MADE
R= 57/58
S= 58/59
T= 60
U= 60/AUG 61
V= 61AUG/62
W= 63
X= NONE MADE
Y= 64
Z= 64
AA= 65
AB= 66
AC= 67
AD= 68
AE= NONE MADE
AF= 62
AG= 63
AH= 64
AI= 65
AJ= 66
AK= 67