More good news....
 

(At the risk of jinxing myself.)
This past weekend, we completed the same trip that we made last year, in the Duramax. That trip was beset with problems coming and going and culminated in being towed almost 200 miles...then the DM problems *really* began!

On our way up this time, it was just the four of us again and some gear in the back....no problems all the way there.
On the way back today, it was us...our trailer...and all of said gear (aside from what we consumed over the two days)...we passed the Brake-Check spot where we got marooned last year.
Passed the next town....and the next....all the way home without issues.
As if to add a cherry on top, when we got home, I backed the trailer into the driveway in ONE ATTEMPT...almost as if to say: "Those problems are in the past!"

Even loaded, there was only one time when I fell below 50 mph along the Highway thru Hell...and then the truck downshifted to 2nd gear and running at 4500 RPM. This was likely due to the incredible headwinds we were fighting all the way back.
Other than that, the truck performed admirably and exceeded my expectations as far as gas-powered trucks have been concerned...I have NEVER been able to pull most of those hills at anything over 40 mph...often less.
It sure makes the trip go by quicker when you aren't grunting over every incline....a lot less driver stress as well.
Yes indeed, I am REALLY liking this truck so far....it's the one I SHOULD HAVE bought last year....instead of the DM.

the 6.2L with the truck.. are real work horses.....

2012, SuperCab, long bed.... 167,000 miles.. and I tow 9,000 pound trailer.... and carry 1,500 pounds in the bed of the truck..
1,800 miles at a time,

last September.. I did 1,800 miles... 3 times over 12 days..

out at 17,000 rolling pounds
return at 14,000 rolling pounds
out #2, 18,000 rolling pounds.

I can not bad mouth Chevy.. retired Chevy mechanic..
but in 2015 I needed a real work truck.... after much research...Ford 250/350 with the 6.2L...
still the correct choice for ME..

I love my 2016 F250 with the 6.2. Such as huge towing improvement over my old 2007 F150.

Even with my 97 OBS Powerstroke, I was still dogging-it up the hills, but I attribute that to the 4-speed transmission.
Plenty of power at and above 2500 RPM, but then the tranny would upshift and the engine would bog.