The floor panel under the 47-54 Suburban "jump seat" is often rusted out (it is in a heavily-scuffed area). There was some sort of rough-looking raised panel under the seat. I think I can find an old post of that floor pane/area/riser - I'll post it here, if I can find it.
Attached below is a 1959 Suburban floor panel that seems to be in very good condition. Does anyone know what years that panel looked like the panel below? My guess is at least 55-59?