I'll probably be testing the Duramax longevity.

[Irish80]

Well I've had the truck 2½ months and it just rolled over to 10,000 miles.  We'll see how this redesigned l5p and 10 speed hold up.  Anybody else racking up the miles yet?

[Haftahunt]

Tomorrow will be 2 months and I’m almost at 8k....besides the hard downshift when coming out of highway speeds I’m happy with the 10 speed....18mpg average ain’t too shabby either!

[CRApex]

6000 on mine...Everything works great.  I haven't noticed any hard shifts up or down, towing or empty.

[Irish80]

1 hour ago, Haftahunt said:

Tomorrow will be 2 months and I’m almost at 8k....besides the hard downshift when coming out of highway speeds I’m happy with the 10 speed....18mpg average ain’t too shabby either!

I've had 4 or 5 hard shifts when speeding back up after a construction zone or going up a hill.  It's a little unsettling and I mentioned it to the dealership when I took it in for something else. They asked if there were any lights on, I told them no, and that's pretty much as far as that conversation went.