Yes. (and no). The switch requires two wires for the hi-lo positioning of the stators and kick down. I have an ST400 from a '67 Electra that has no horseshoe, only two dimples and a single blade, but the pump and TC were Switch Pitch parts. Pulled the pan and the wires are there. So, either it may have been at a time that Buick started "un-switch pitching" and it left the factory working as a typical ST400, or it was a rebuilt and they disabled the function by changing the switch to only run the kick down. But why the pan is like an ST400, I am not sure. Anyway, Jim Weise has it and is teaching it to be it's younger self again.
I would think you would have to have 2 plug......1 kickdown, 1 for solenoid for the switching. But not all transactions with 2 plugs are switch pitch, seen some have a smog switch for some reason not sure what it did, but was a later 70's or early 80s trans
