When I had an ST-300, I used a microswitch to call for a downshift at WOT. The transmission won't downshift if the car is going too fast for the lower gear, but under all other circumstances if you floor it, you want it to downshift.

http://pg.photos.yahoo.com/ph/rossettij@sbcglobal.net/album?.dir=f1a6&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos

Mine was triggered by the mechanical linkage on the secondaries of my Quadrajet. Yours will probably be different. But that's why I recommended the smaller and more easily positioned microswitch.

Now I've got a TH-350 and it has a downshift cable.

I live in DePere, which is on the south side of Green Bay.