Anybody know of a connector in a D shape, about the size of a D15 (game
    port adapter), with 4x15 set of contacts on .050" centers?

This sounds exactly like the "high density" connector used on the (sync)
serial interfaces of cisco routers.  I'm pretty sure this is a molex part (a
quick look at their web page says it's probably LFH type 70929.)

I can almost certainly dig up a (possibly broken) cable with this connector
from my dumpster-diving collection.  However, cisco cables connect different
pins to achieve different line types (rs232, v.35, etc, DTE/DCE - about 10
different types of cable), so I don't know whether it has all the pins on
the high density connector connected to wires...

BillW