DIG: Thanks for weighing in with this information. I don't know if I am going to need any right now, but someone else might have already made that decision and might buy them from you. I'm just not quite to that point as yet.
JWA: I don't know if you can use this information, but I came across it after reading your post:
Ford Tech Tip: Steering Wander on Ford E-Series Vans
Dropped air pressure in front tires to 62. Much better feel that's on the heavy side and just about right, but still a bit of play in the steering wheel - maybe about a quarter inch or so. Might be right as far as tire pressure goes. Drove it about forty miles in a steady rain on two different highways in moderately heavy traffic. One steep grade going and coming back, and one on the way to the highway from the house. Both grades between 10 to 12 or 14 degrees. Rough spots on both grades causing a bit too much body roll, with the one at highway speed in a curve causing me too put my left hand on the wheel. Maybe a bit too much up and down movement in these areas as well. It was a relaxing ride with one hand steering despite the weather and the traffic; lots of semis on the road.
All comments about what I might do next are most welcome...and thanks again for all the help to this point!