Here's the breakdown using an online decoder...
Decoding of Fender Tag: Botttom to Top, Left to Right
Code Description
E55 340-4 Barrel 69-73
D34 TorqueFlite Automatic Transmission
JH23 J = Dodge Challenger
H = High
23 = 2 Door Hardtop
H3B H = 340 240HP(net) 1-4BBL 8 CYL
3 = 1973
B = Dodge Main, Hamtramck, MI, USA
519000 Sequence Number '519000'
TX9 Paint Code: Black / Black Velvet
A6X9 Trim Grade/Style/Color
A = A Class
6 = Vinyl Bucket Seats
X9 = Black
000 Upper Door Frame: Full Door Panel
517 Date Built: 5 / 17 / 1973
234447 Order Number: 234447
V1X Roof Type OR Color: Full Vinyl Top - Black
U Built to Specifications for USA Order
B41 Front Disc Brakes Some Yrs. Power
C16 Console w/ Buckets
C56 Bucket Seats 1972 up
G37 Left Hand Remote, Right Hand Manual Chrome Mirrors
H51 Single Air /w Heater
J54 Hood Insulating Pad
L25 Trunk Compartment Light
L31 Hood / Fender Mount Turn Signal
M21 Roof Drip Rail Moldings
N41 Duel Exhaust w/o Tips
N42 Chrome Duel Exhaust Tips
N85 Tachometer
R38 AM / FM Stereo Search
V5X Black - Mouldings - Protective Insert Body Side
26 26 in. Radiator
EN2 End of Codes Assembly Line 2
I believe the "special order" cars had an "S" ahead of the order number. Cool car BTW!