Nice links, I have one of the H8571-HP adapters which
is listed. What 
 about the RJ45 ethernet to MJJ adapters (I have one Amphenol
482560001)?
  
 Is that a coupler that you plug an MMJ cable plug in one end an an RJ45
 cable plug in the other? 
 
 It has a female socket for the MMJ plug on one end and a male RJ45 plug
 molded into the other end.
 DEC and Digital Equipment
 Mfg Part Number 482560001
 Product Description Part Number: 482560001 New, Used, Refurbished, and
 Repair of AMPHENOL RJ45-M TO MMJ-F ADAPT. 
 
Are you sure this has anythign to do with ethernet? My guess is that it's
sued to linke DEC serial ports (MMJs) to the modern 'structured wiring'
found in soem buildings. You'd use them in pairs, one ant each end of a
building cable so as to connect the 2 serial devices.
And, please, it's not RJ45 unless you are taling about a particular US
telephone wiring scheme. 10baseT ethernet, etc does not use an RJ45
conenctor. It's an 8p8c.
-tony