I have a spare 85 switch you can have. I swapped to a 86 wire harness and got the relays and all switches with it. swapped to the 86 wiper motor to get all to work correctly.

do you have a non delay wiper switch on hand?

don't know why its different? it is a big metal/heavy box looking switch.
the plastic delay relay box under the dash is another thing hard to find.

the bus bar on the wiper motor is different than the others also. so check you wiper motor for the big square delay relay bus bar. found one at napa for the 85 delay 90$

I used a 85 non delay wire harness on my 88 440 truck and have yet another 85 delay switch there also. 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.