Same machines really, the 3D's ring high with the older coins down deep is the only real difference. Even nickels will ring with high tones! I have heard that the newer CZ3D's don't have near the depth of the older 1021 models or the CZ5 to CZ3D conversions that NASA-Tom Dankowski did. I have many times considered sending my CZ5 to him for conversion but Tulsa doesn't have enough old sites to justify it, plus I am now used to it as is, changing things after I've learned it so well might be a step backwards, plus it already has mad depth, I can easily dig a dime at 9"+ and quarters even deeper! Maybe I should send him my CZ6A, which is my backup fisher?