Retainer ring for center cap?

[fullahotair]

I need the metal retaining ring for the 86/87 wheel center cap. My center cap came off the other day, I found the center cap, but the retainer is gone. I am not sure if you can take off the retaining ring or not. I know i can get a complete new cap for 20 bucks from G-body parts...

Thanks
Nathyn