[hypoxia]

I don't think you will be using the CC at all in the big mountains.  They are twisty turney and speed is not your friend.  Truckers say the speed you are at when you crest the hill is the speed you shoot for going down.  My method of descent is to be slow enough using the Jake to rarely if ever touch the service brakes.    I do not want the service brakes to be warm in the event I need them when I come around a curve into an accident scene, rock slide or herd of elk.  I pass trucks going up and they pass me going down.  I look for the yellow speed advisory signs and go around curves at that speed or less.  When the furniture starts moving around I start hearing copilot noise.

The Cummins ISX 600 and Allison 4000 is the same combination I had in my last coach but the gearing and weight are different.  I find myself manually shifting the Newell more often on steep narrow switchback roads.  I spent a fair amount of time in 1st gear last summer on one road in the Rockies.  I was told that West Virginia is so twisty you can stick your hand out the window and hit yourself on the back of your head.  I found that to be true and couldn't use the CC because of it.

You'll figure it out quickly and although the Cat is different the concept is the same.  Everyone is giving good advice.