From the Serial Number Research Project Thread:
http://glocktalk.com/forums/showthread.php?t=1287557
DN - G-19 - March 1988 -
1st Gen. - First G-19s imported
DY - G-19 - January 1989 - 2nd Gen. - Slide stamped MPDC, date code 'ETD'
(apparently MPDC is the Metropolitan Police of Washinton DC)
The DN, if it is Gen1, is a rare Glock indeed. Very few Gen1 G19's were made. The Gen1 should have a smooth "pebble-like" texture all the way around the grip. A Gen2 would have serrations on the front and back of the grip.
See Butch's post here for pictures of the difference between a Gen1 and Gen2 G19:
http://glocktalk.com/forums/showpost...1&postcount=19
The three-letter code on the barrel corresponds to the test-fire date in Austria:
The first letter is for the month:
E...Jan
L...Feb
N...Mar
B...Apr
S...May
Z...Jun
G...Jul
P...Aug
I...Sep
C...Oct
V...Nov
A...Dec
The last two letters are for the year:
O...0
W...1
K...2
R...3
F...4
M...5
H...6
Y...7
T...8
D...9