I need one with a couple of RS232 ports (because the KDF11-B comes with a
  couple of SLUs)
 
 I'm guessing you need one fitted with those small (10-way?) AMP connectors.
 I believe it's known as a D315 panel.
 
Thanks ! It appears as an element of the 11/84 in some sellers.
 Eventually, it would be great to get other panel with one Ethernet
  connector
 plus others.
 
I can fix you up with a DEQNA/DELQA cab kit if you need one.
Thanks again. Let me receive the box and the back panel and I shall tell you
something.
By the way... I am using one old IBM XT to enclose one EDSI hard disk to use
with the PDP. I have too a couple of RX33 diskette units (more or less
standard, not RX50), but I don't know if I can use them with one PDP-11.
Regards
Sergio