There is another way to do this:
Use transgo's kit to control the line pressure
4l60 line control And then use a pair of toggle switches to shift the forward gears, I did this for quite a while before installing a controller.
Use a vacumm switch and a relay to control the L/U converter.
Or if you don't like the toggle switches then I can provide a kit that will run the gears - you will need to move the shifter to select the gears though.
