On Wed, 05 Aug 2009 12:44:28 -0400, Little John
wrote:

Our truck, a Navigator, has a button on the end of the shifter lever.
It locks out the top gear, so the box doeesn't hunt for gears.

Casady

I could just drive in 4th, which would lock out overdrive, but don't
do it unless I'm towing in a pretty hilly situration.


It's better for the transmission to lock out overdrive anytime you are
towing.