I am building a desktop cable to connect a 51637223 aux display harness to a PCM universal telematics harness. 

At this point I think I have it pretty much done. Waiting for a specific connector to arrive.
Here is the pin out of the display cable as I traced them. I then added a wire from the switch back down to the 16 pin so it can trigger a switched relay built into the desktop harness I am making.

I am hoping I can send this all to the NH dealer and get software installed this winter. I have a pro1200 with no software and a Verizon PCM unit. So far as I can tell the pro1200 uses the same pinout as the older displays. However, I can't tell if any of the extra connections are needed or not. 
I should add the PCM telematics cable has 4 CAN bus and 2 RS232 serial. I made the desktop power section so CAN 1 and 2 from the display can connect to the PCM as well as the serial port so it should allow file transfer as well. From the PCM harness it seems that should be all that is needed.

(16pin display kit (full).jpg)

(26pin AMP display early to 700 (full).jpg)

16pin display kit (full).jpg (105KB - 10 downloads)

26pin AMP display early to 700 (full).jpg (162KB - 6 downloads)