One thing that was discussed by some of my buddies was that they screwed up when they made the Cuda front rubber bumper was they only made it for a 1970 and not a 71.
The lower grill opening is narrower to match the lower valance opening on a 71 so the 1970 bumper doesn't work.

Gene Gregory made his all off a 71 mold and then cut out the opening when needed for a 1970 Cuda.

That probably had a negative effect on AMD's sales of the bumpers.