Thanks for the steer to the Chrysler Master Service Conference booklet page posted. I'll look into the working angle, and that may be just the problem. Years ago, I ordered a set of leaf springs and had them installed. They lift the rear end up, and the car sits high at the rear. After reading the repair pages on the subject, all the indicators point to a wrong working angle. I'll see if I can get the springs re-arched and bring the angle to specs.
It may be a while before I can get the car to Albuquerque, but I'll let the club know what comes of the fix when it happens.