Borrowed from some Brethren over on earlyvaliant,org. this is for Valiants, but should be 95% correct for a Dart too.
There are five main areas to decode on a fender tag: the SO, NUMBER, BDY, TRM, and PNT.
SO and NUMBER go together as the Shipping Order number. It consists of a 4 digit planned delivery month/day code, then a plant production sequence number.
The date is decoded as follows...
JAN...1,FEB...2,MAR...3,APR...4,MAY...5,JUN...6,JULY...7,AUG...8,SEPT...9,OCT...A,NOV...B, DEC...C.
For example: June 23rd looks like this...623. October 3rd looks like this...A03.
Next is the BDY or body number indicating the model & body style.
Valiant V 100--------------------Valiant V 200--------------------Valiant Signet----------
------------------6cyl----8cyl-------------------6cyl----8cyl--------------------6cyl----8cyl
2dr Sedan......111.....V11.......................131.....V31..........................***.......***
4dr sedan......113.....V13.......................133.....V33..........................***.......***
4dr wagon......156.....V56.......................176.....V76..........................***......***
convertible.....***.......***.....................135.....V35.........................145.....V45
2dr HT sedan.***.......***.....................***......***.........................142.....V42
-----------------------------------------------------------------------------------------
Barracuda
----------------------------------6cyl----8cyl
2dr Sports Hardtop...........189.....V89
Next is the TRM, or trim code that tells the interior color & fabric.
Code--------------------Cloth-----Vinyl-----Color
L1B,K1B....................*............*..........Blue
L1R,K1R....................*............*..........Red
L1T,K1T,L2T,K2T.......*............*..........Tan
L4B,K4B....................-.............*..........Blue
L4R,K4R.....................-............*...........Red
L4T,K4T.....................-.............*...........Tan
L8T,K8T,T8T..............-.............*...........Tan
L5B............................-.............*..........Blue
L5R............................-.............*..........Red
L5T............................-.............*..........Tan
H4B............................-.............*..........Blue
H1B...........................*.............*..........Blue
H4Q...........................-..............*.........Turquoise
H1Q..........................*..............*.........Turquoise
H4R..........................-...............*.........Red
H1R..........................*..............*..........Red
H1T..........................*..............*..........Tan
H4T..........................-...............*.........Tan
H4X..........................-..............*..........Black
H1Y.........................*...............*.........Gold
H4B........................-................*.........Blue
H4Q........................-................*.........Turquoise
H4R.......................-.................*.........Red
H4T.......................-.................*..........Tan
H4Y......................-.................*..........Gold
P4B......................-.................*...........Blue
P4Q......................-.................*...........Turquoise
P4R......................-.................*...........Red
P4X......................-.................*...........Black
P4Y......................-.................*...........Gold
M1B.....................*.................*...........Blue
M1Q.....................*.................*...........Turquoise
M1R.....................*.................*...........Red
M1T......................*.................*..........Tan
M4B.....................-.................*............Blue
M4Q.....................-.................*...........Turquoise
M4R.....................-................*.............Red
M4T.....................-.................*............Tan
M5B....................-..................*............Blue
M5R....................-..................*............Red
M5T....................-...................*............Tan
H2B....................*..................*............Blue
H2Q....................*..................*............Turquoise
H2R....................*..................*............Red
H2T....................*..................*............Tan
H2Y...................*...................*...........Gold
H5B...................-...................*...........Blue
H5Q...................-...................*...........Turquoise
H5R...................-...................*...........Red
H5X...................-...................*...........Black
H5Y..................-....................*...........Gold
Last is PNT or the Paint code that tells the exterior color.
AA1=================Gold Poly
BB1=================Black
CC1=================Light Blue
DD1=================Medium Blue Poly
EE1=================Dark Blue Poly
HH1=================Copper Poly
JJ1==================Light Turquoise
KK1==================Medium Turquoise Poly
LL1==================Dark Turquoise Poly
NN1==================Barracuda Silver Poly
PP1==================Ruby
SS1==================Ivory
TT1==================Medium Red Poly
WW1=================White
XX1==================Light Tan
YY1==================Medium Tan Poly
Want to know if it's a Formula S? On the fender tag of a 65 Barracuda, look for the 'ABC'.... under the AB will be a '31' for the 273 4bbl 235hp engine. Under the C will be a '2' for the formula "S" package. The car should also have a tach in the dash....