71 did have a fender difference. the cuda fender in 71 had 4 gills at the back of the fender (above the body line behind the wheel well), while the barracuda and gran coupe did not have gills. The barracuda, gran coupe and cuda are just option packages. The cuda model is the performance model, usually had upgraded suspension, flashier trim, bigger horsepower engines, etc. The gran coupe was the more luxurious model with things like leather seats and overhead console. The barracuda was the base model. should be noted that you can order some options across the board like the leather interior could be ordered on a cuda model.