66 Dart Fender tag decoder

She just had a birthday last month, Dec.6 (built in 1965).
L=Dart P=premium price class (Dart GT) 23=2dr hrdtp.
P4W P= Premium trim grade, 4=bucket vinyl, W=white & black color
KK1 roof color K=medium turquoise metallic. body color K=medium turquoise metallic. 1=monotone, top and body the same color. upper door frame color B=black.
a6=console, b4=bucket seats, p6=mirror outside lh remote.
AB 31=273 2bbl 180h.p., C5=torqueflite, E1=??? this could be 1 of many posible things. Could be air, tinted windows. Not sure on that one. Sorry, don't have all the answers ,I'm still learning too. R1=Music master radio 2 watt. TURN IT DOWN , YOU'RE HURTING MY EARS!
They are three # codes and can be kinda confusing. The code for the radio is 421, air is 411, tinted glass is 521, bumper guards ft are 481. Someone might help us with the "E1" code, I hope. Congrats on the car, It should be fun. Ray