I run the same setup, lock o/d off in the hills and grades, if you try to run cruise it will down shift in o/d a lot, 8.5 mpg gcvw @ 14,500.

so i run o/d off and crusie off most of the time.

 

When the tranny engineer speaks...I would listen. LOL...just my 2 centavos worth!

Joe

 

Check your owners manual for that. I remember something about that on one of my trucks in the past. If it says to keep it off I would, and I used to, except long downhill grades where engine braking wasn't needed. Trust the folks that design these things as extensive testing tells the story.

 

HAHAHAHA right on!! if MK says it, well then thats enough said!!! LOL

and BTW my names Joe too.

 

16,000+ lbs with a 5.4L

You must have been towing in 4x4 Low Range