The Banshee trans has a tighter ratio then the RZ does... The shift drums are identical, the shift forks, however ARE different.. Banshee forks have solid guide pins, where as the RZ forks have a roller for the guide pins. Some say it doesn't make a difference, some say it does.
I have a nice set of extra RZ forks and drum, that I might be willing to part with.. Be careful of the 2 Stroke Shop.. there has / had been lots of drama surrounding that place on the RZ / RD forum. I, however DON'T know from experience.
Mike