Part numbers listed below indicate interchangeable parts. These parts share the same size, parameter, function and compatibility. However, please note that items from different brands may have minor variations.
FD509, FD-509, FD 509 - STANDARD MOTOR PRODUCTS, SMP, BLUE STREAK
DG521, DG 521, DG-521 - MOTORCRAFT, FORD
8L3E12A366AA, 8L3E-12A366-AA - FORD
8L3Z12029A, 8L3Z 12029-A, 8L3Z-12029-A - FORD
522071, 522-071, 52-2071 - CARQUEST