The door scuff plates are the "finish panel" located at the top edge of the rocker panel where the carpet meets the top edge of the rocker.
I needed to replace a damaged scuff plate on an '86 SVO that I was working on recently. The easiest option was to simply go online and order replacement plates from one of the various Fox Body parts vendors. Daniel Carpenter makes a nice reproduction in charcoal at a reasonable price.
What I received is a part, that while it can be made to work, it is not "assembly line" correct. I use the term "assembly line", because I have found a few details that don't match up. I have attached several pictures as reference.
The 1986 MPC lists the correct part number for the SVO as E4ZZ-6113208-B.
The reproduction part uses the part number of D9ZZ-6113208-G. The engineering number molded on the back side is F0ZB-6113208-ABW.
The oem part has the engineering number molded on the back side of E2ZB-6113208-AWA.
The differences between the original and reproduction are the length and a small tab or flange at each end is missing on the repo. Please refer to the pictures. The original is 37 15/16" overall and the repo is 38 5/16" overall. This slight difference in length results in the mounting holes not lining up. Once installed, probably never noticed. The missing tabs or flanges is interesting.
I have a set of NOS plates, part number E4ZZ-6113208-B dated 11/11/96. They are the correct length of 37 15/16", but they too are missing the tabs at each end. They are still sealed in the original packaging, so I can not confirm the engineering number molded on the back side.
The missing tabs at each end has me puzzled as every original car that I have looked at have all had these two tabs, yet the NOS part does not. This is an easy detail to spot if you are looking for it.
I don't have an '87 and up car to reference, but obviously the repo part with the later F0ZB engineering number is for the later style Fox Body cars. Maybe someone can chime in on what they may have in their cars.