OD is usually a "no load- - - -get on down the road" gear for keeping up with traffic while running empty on the way to the hauling job. Once the truck is earning its pay, stay out of OD unless you've got a Brownie with an OD position so you can split every main box gear three times.
We also called shifting a Detroit-powered rig "rowing it with the shift lever!"

LOL!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!