I've been told you can have the overdrive stay off when you start the truck. I tried to search for this solution but can't find anything. Most of my daily driving is around town and hate when I forget to turn off the overdrive and hit the right speed for lockup and overdrive all at once, kinda bogs everything down.

 

The instructions are on Dave Fritz's webpage. Here's the link. O/D Inverter I've been meaning to do this for quite a while too.