D13 = 3 Speed Manual Floor Shift
E44 = 318
B43 = Front Disc brakes/Manual drum rear
C56 = Bucket Seats
G37 = LH REM/RH MAN O/S Mirro CHR/RAC
M21 = Drip Trough Moldings
R11 = AM Music Master Radio
TB3 = Super Blue
Just did a quick pass. Dunno about GM stuff
Then to add a little more...
1973 model year Barracuda (Not a 'Cuda)
SBD= 4/30/1973
V6X=? White longitudinal Stripe for 1973?
Wonder why TB3 listed twice?
I wonder what the interior color is? The code, A6X9, I don't know, but it isn't a blue interior(It would be B5xx) so with a TB3 exterior, I would guess black or maybe white.
As far as the GM tag, I need to see it closer to figure i out.
Got a bigger pic?