Sorry this reply is a couple of years late. Here is a complete breakdown of Bill A's 1957 Lincoln's data plate.
Starting with the serial number 57WA21507L: 57=1957 model year; WA=Wayne, MI assembly plant; 21507=16,507th 1957 Lincoln scheduled for production at the Wayne plant; L=Lincoln
The second line Body Specif. (Model) BAJ=Engineering code for 1957 Lincoln; 60=2-dr hardtop, B=Premiere Series; (Color) 136=Two-tone scheme, Starmist White with Oxford Gray; (Trim) 734=White leather Bolsters with Black leather accents and trim; (Date) A5=January 5, 1957 as the day your car was scheduled for production, (Rotation) 398=398th car is a production cycle.
For 1957, all Lincoln production was conducted at the Wayne, Michigan assembly plant which also produced Mercury automobiles that year. A total of 15,185 Premiere 2-dr hardtops were produced for the 1957 Lincoln. A total of 41,123 1957 Lincolns were produced. . The highest serial number issued for 1957 was 57WA46232L