These are pictures of the bumpers from a 1971 2800 CS. Notice the protruding bumper mounts brace. They stick out about an inch or so. This type attaches to the car direct (no bracket). The bumpers for 3.0 CS the brace is recessed, and has from what I remember , I think only one bolt on the bumper side. It requires that look number bracket.
The pictures from the trunk are from the 71 2800 CS I am restoring now. That should give you an idea .
The pictures from the trunk are from the 71 2800 CS I am restoring now. That should give you an idea .