>PATH =  /PRODUCTION/ARCHIVE
>Guest ok = yes
>Guest only = yes
>Write = yes

You'll most probably get write access errors because MGR.SAMBA (the
default Samba/iX guest user) is unable to create files in the other
account (group ARCHIVE.PRODUCTION). You might be able to verify this
by trying a BUILD somefile.archive.production from MGR.SAMBA logon.

It might be worth to either try a subdirectory /PRODUCTION/ARCHIVE/xy
and open its permissions wide enough (e.g. rwxrwxrwx) to allow MGR.SAMBA
create files there (in ACD terms this would mean TD,CD,DD permissions)
  or else
adjust the smb.conf file to use a different guest user for this very
share, i.e. add "guest account = mgr.production" or something similar.
You'd want to check /usr/local/samba/bin/smbstatus to see if the PC
user actually gets access on behalf of mgr.production after the change.

I've not tried both of the above ideas myself, so your milage may vary.

Lars.