The spoiler looks like it's mounted properly to me! The only reason it looks wrong is that you couldn't get a spoiler from the factory in 73, you had to add it yourself. I think it looks great!
The car wasn't originally painted Black. I decoded the tag numbers you posted.
L31 fender turn signals
M21 drip rail moldings
R11 music master am
V6X = Sport Stripes Longtudinal tape (Black)
EN2 = End of Codes on Assembly Line 2
JYS = no such code
O = no such code
341 = no such code
C56 = Bucket Seats
G35 = Left Hand Outside remote chrome mirror
L25 = trunk compartment lamp
JY3 = Honey Gold (body color paint)
A6X9 = A class, Vinyl Buckets, Black
000 = upper door frame color (because E-bodies had full door panels no color was coded as no metal was exposed)
418= April 18th 1973 scheduled production build day
449707 = Vehicle order number (same number was on the invoice used to order the car)
E44 318
D13 3 speed
BH23
I hope this helps and if you have any more questions just ask,
Doug Lepak
The Steering Wheel Guy
web site:
http://drive.to/stwheelsSpecializing in MOPAR wood grain steering wheels