help needed on AMI S-81 speaker

A few weeks ago I aquired a AMI S-81 speaker and after receiving it
and having a good look at it I do have some questions:
- does this speaker originally have a back plate?
- whats in between the speaker and the front casting? Is there a
grille covered with cloth or only cloth?
- could someone send me a photo from the back of a S-81? I would like
to know what kind of speaker should be inside.
I guess mine has a wrong speaker so in fact I only have a case and the
front casting.
Whenever someone has a decent AMI S-81 speaker for sale I would be
very interested, the S-81 is the round speaker with "Music by AMI" on
the front.
Also I'm looking for a Wurlitzer 5100 speaker.

Thanks you very much,
Rene