Not sure if it's the same with Cudas, but my 73 Challenger was a direct bolt on using a set of 70 front and rear brackets. Nothing had to be modified, other than filling in the top holes from the bumperettes, which cost an extra $5 when I had the bumpers rechromed. I did add the 70 style bumperettes on the rear, but again, nothing had to be modified, other than massaging the aftermarket rear valence to line the cutouts up.