I have the 2500 6.0 with the 6 speed tranny and 4.10 gear. I'll be thru the Smokies again in about 10 days and then over to Myrtle Beach. You have all the info you need in the above posts to explain how to handle the mountains. Your 3/4 ton has beefy 4 wheel disc brakes, a strong transmission and plenty of horses under the hood. A reminder that when you hit your brakes during a descent while in tow/haul mode, your transmission will also downshift to help reduce speed. If your a little nervous or white knuckled, it can cause you to jump in your seat the first time it happens. You have the right truck and after a bit of windshield time you will have the confidence as well.