Hard to find Armalite AR-17 parts

I posted this on the wanted forums but I need to spread the word as much as possible. I am looking for a butt plate and grip cap for a Armalite AR-17 12ga. auto shotgun. I realize there were only a couple thousand of these made and the parts will be hard to find but maybe I will get lucky. When and if I find the parts, I intend on selling this gun here in an auction. Could use some help. Thanks