One of the guys who works for me has an 06 LBZ with 298K miles on it. The truck runs and shifts like brand new. He has a tuner in it and the truck hauls ass. Put a piece of tape over the odometer and you would never know the truck had over 70K miles on it. 06 and 07 were the best years for the Duramax in my opinion.

Just picked-up a very nice 2007 2500HD Classic 4X4 with the LBZ/Allison combo and the LT3 trim package.
Prev owner was let's say very mature and exceptionally anal abt this truck. She looks and drives like a new truck. Bone stock except for the Magnaflow exh and Airaid air filter assy. Never had a tuner or fifth wheel.

One kinda cool thing the prev owner added was a set of fog lights under the rear bumper. They come on with the bed light (via relay). Looks like they would work great when backing down a dark boat ramp or changing a trailer tire on the side of the road. When not in use they fold up under the bumper so if they come on, they'll shine straight down.