The gen crown will not fit on a rep tube so you will have to change the tube also. The modern sub I have has a smaller diameter hole in the case for the tube so the hole would need to be drilled out and retaped, not sure if this is the case with all moderns though (my vintage one was a direct swap). Rember The Zigmeister saying some were just a swap but if I remember correctly they were not a TW case.