Still hoping to find out what the "L557" stands for?
This is the info I get. =================================================
1969 Pontiac Firebird Sport Coupe The paint was Cameo Ivory with Cameo Ivory upper body color. The trim color and material were Medium Gold Vinyl. This car was number 521,616 built in the 3rd week of April at the Van Nuys, California plant *(4).
Special Note:
*Alert* (4) Your body tag used a not so common code for the Van Nuys, California plant (VN). The code that was normally used was "LOS" for Los Angeles. You should also note that the VIN uses "L" for the Van Nuys plant.