Hey Mike, the kisck down wire for the ST300 is about the same set up as the kick down for the TH400 3 speed. Maybe you can cross refernce looking for that info.

But for the most part, you should be able to order the parts... especially from an outfit like Lokar (switch, bracket etc.) and then just run a wire from the switch at the throttle linkage to the switch on the side of the tranny...

I'm sure others can give you more detailed info!

Brett - 67 Drop Top 455!