Can anybody tell me what color the wire is that plugs into the down shift switch on a turbo 400? I don't know what year the trans is.
I changed the dash over from a sweep to an SS style, I don't know if that makes any difference on the wiring harness.

If you have a correct 70 harness, the plug will have an orange and a black wire going to it. The orange is the power for the kickdown, and the black is the ground signal for the TCS system, probably not needed for your application.