I have some updated info to share. In addition to my post here, I also posted on a couple of other sites. No one had any conclusive info or thoughts to share. I was finally able to connect with someone at Mark Levinson. They confirmed that these are simply pass through cables. So, in terms of pinout and wiring, it is simply a matter of making the same connections on each end, i.e., pin 1-1, 2-2, 3-3, etc. They also confirmed that these cables are shielded. However, they did not know whether the shielding was attached to the connectors, and if so how (e.g., on both ends, only on one end, etc.). Apparently, all of the people who worked on these units are long gone.
I am familiar with how shielded AC power cords are built. The shield is typically connected only on one end, the end that plugs into the wall. As I understand it, if you connect both ends the sound is degraded. Not sure if the same considerations apply here. It does not seem so, since there is no indication that there was a specific way to plug in these cords, i.e., either end could go into either component. That suggests that either both ends of the shield were attached, or neither end was attached. If anyone has any thoughts on that, let me know. Otherwise, I might start a separate post on how to build a shielded DC power cord.