The connector is a DB-15 with unusual latches, but if
you ignore the
latches then a stock DB-15 will work.
Actually, it's a DA15 (the DB15 doesn't exist AFAIK), and normally has the
standard slidelock latches.
I had to make an AUI cable for my PERQ. That machines has normal
screw-down jackposts on the ethernet connector (it's an
otherwise-standard DA15, with the standard pinout). So I had to make up a
special cable with screwlocks on the male end and a slidelock on the
female end.
The only difficult bit to find was the cable. Plenty of places would sell
me a 100m reel of it, but I only wanted a couple of metres. In the end I
found a freindly network guy who gave me an offcut. IIRC it had a brown
outer jacket (just as another data point!).
The cable is 4 twisted pairs, but one of them (the power pair) is
supposed to be thicher, to carry more current (obviously the
characteristic impedance of the power lines doesn't matter!).
-tony