New to Forum - Metz 204KW 3-D

Hello friends:

My name is Carlos and this is my first post.

I have a Metz 204KW 3-D radio in perfect condition, working fine.
I have searched the web but I have only found information about the 304 model.

Can anybody help me with some information about this radio?

1-Year of fabrication (I suppose it's the late 50s)
2-Technical specs?
3-Where can I find spares for it?
4- Although I am going to keep it, which could be its market value?

Thanks in advance

Languedoc