Are you actually trying to modify an AirPort Extreme to hold a hard drive? It sounds like it. You lost the sata ribbon and rubber plate and metal plate for a 2013 Time Capsule? Sounds a little strange. How do you lose all that?
Can't help you with those parts I'm sorry but if you are looking to get them to try the Extreme mod then think twice as the logic board does not even have a point to plug the sata ribbon/cable into.
Just thought I would mention that. Apologies if I am misreading your post.