Many Corrado owners have been wanting to swap in a moonroof due to a variety of reasons, and some people have been installing moonroofs from other VWs. You can use either a B3/B4 Passat moonroof or a A3 Jetta/Golf moonroof, click on a link for more info and pics concerning the install. Corrado Headliner Removal Passat A3
PLEASE NOTE: I can not offer technical advice on an install nor do I sell moonroofs, I simply archived this info.