I'm changing out my TH350 for a 400 and I need to find the wire harness for the kickdown Any help would be great thanks

 

The harness is built into your existing harness it’s usually just taped up. You will need the switch and bracket and either remove the tab for the th350 kick down cable or replace the gas pedal.

 

What year is your car?

 

it's a 68 cutlass s it cam with a 2 speed jetway I changed it to a 3 speed so I never a wire running to the trans

 

The Jetaway uses an electronic kickdown just like the TH400 so all of the wiring should be there unless it was torn out when the TH350 was installed. Also the kickdown switch should be mounted on the gas pedal, again, unless it was removed when the TH350 was installed.

 

If the switch and wiring is still under the dash (pink and orange wires with a 2 terminal connector body) all you need is a series 56 male terminal and enough wire to reach the kickdown solenoid. American Autowire sells the correct wire and connector body for a factory look. It would be great if all the original stuff is still there, makes the swap easy.