First off, I want to thank you for all the info in that post. It was extremely helpful.

I went to remove the wipers and the splined portion pretty much just crumbled to pieces. Apparently the metal had just become very weak and brittle over the years. So after that, I went ahead and removed the retaining pin from the wiper post stub and went checking local sources to see if I could luck into a replacement part. I had no such luck though, of course.

What I decided to do was get some nylon bushings from Lowes, then drill a hole in the arm and tap the hole that had been used for the retaining pin to allow me to use a set screw to hold the wiper in place. This idea would have worked great except that there is apparently a small bit of play in the positioning of the wiper post stub, and so when I lined it up and drilled the hole in the arm, it was slightly off from where it should have been. I ended up slotting the hole to allow me to adjust it to where it needed to be, and when the screw is tightened down it seems to hold it quite well.

I also noticed that during a sweep, the wiper blade touches the rubber weatherstripping on both the outed edge of the windshield and also on the bottom edge. Out of curiosity, I loosened the set screw (which allows the arm to rotate back and forth slightly) and tried it again. This time, the wiper blade stopped about 1" from the outer edge and about 1/2" from the bottom edge. So I think I may end up leaving it slightly slotted and loose, and using some loctite to keep the set-screw from working its way out.