I have a spare 85 switch you can have. it works as far as parking the wipers and low/high but the delay part of the switch kills them where every they are till you either turn off so they park or get low/high speeds.
Scratch was kind enough to send me a switch. I tried to bench test this and didn't have much luck. As far as I can tell it's just as he stated above... When in the delay mode it does not have continuity on the tabs stated in the FSM. The other positions check out. I also dug out the parts I wanted to use for the Delay upgrade. I realized that the delay box I had wanted to use is not the correct part number even though the plug for it is the same. Its for a 1990. truck/Ramcharger. So I am back to where I started.... I don't have any of the components to do this delay upgrade.
I still don't know why the switch and delay box part numbers changed a few times between 81-85.