I can't understand why people buy anything off e-bay. diggs, can you post a couple of pics of the pieces you have left over, and the rear of the plane? Maybe somebody can figure out what you need to do. If you have a good LHS in your area that deals in r/c planes, maybe they can show you.

Not really sure what to offer for help. You said "rudders" (plural) in your post. A Cub has only one rudder. Do you mean elevator? There are two halves.