Interesting. Althought I can’t see a reason for that since motors are the same and switches are virtually also the same as far I recall. And wiring to bulkhead is also the same, running into the same 4 ways plug. Engine bay harness side is also the same.
A bodies are also the same. In fact talking on A bodies the only difference is between foot pump washers or electric washers. This are the only physical difference on switches where electric washers wiper switch are press in shaft and foot pump are fixed shaft. Sooooo if you install a electric washer system on a foot pump car, you need to add the wire running between switch and bulkhead (and of course on engine bay side aside the change the reservoir)… on A bodies at least. Even this, plug to switch remains the same, just one cavity left empty on foot pump cars.
Also up to 74 on A bodies, two speeds wipers are foot pump, while 3 speeds are electric pump washer. Then from 75 all are electric. Maybe similar to E bodies hence why the wire difference you found? Was that extra wire for 3 speeds a brown one?
You can even install a B body switch onto a A Body or backwards and wiring and plugs (if same year) will be the same. But the physical size/lenght of the switch will allow or not this posibility. Thinking the same about the E bodies.
