OD is overdrive. That's your top gear. It's mean for economical cruising, but you have less power to accelerate. You can turn OD off if you are pulling a trailer, if you're going up a long hill and need a little more power, or coming down a long hill and want 'engine braking' to slow you down.

Overdrive like above said. Mainly for highway speeds. Use a higher tranny gear for fuel economy

In the off position the transmission does not shift into overdrive. In the on position it will shift into overdrive and the engine RPM will drop about 30% due to the final drive ratio.

Overdrive. Look it up.

I went through the maual and eveything but I really cant find any information on it. Its the stick on the prnd2l box. The little button on the side you can push it in it says on/ off then it has like OD at the top. Does anyone know what it does?