The JEGS website sells reproductions of original sill plates for vehicles made from 1960 to 1972. For vehicles that do not fall within those model years, JC Whitney's website sells custom-contoured sill plates that can be trimmed to fit. Car dealerships may also be able to order original sill plates.
Car door sill plates are located on the vehicle body, at the location where the door meets the body. They are designed to protect the body from wear and damage. Because of their location, the sill plates are exposed to the elements and are among the first parts of a vehicle to get wet or dirty from outside elements such as mud and road salt.
Older door sill plates were almost always screwed into place, whereas newer ones may be screwed in or held in place with metal retaining clips. Plastic sill plates may warp or crack over time, requiring replacement to keep them from interfering with the door.