Just got my 06 2500 and had a question about the engine upon shutoff. After I turn the truck off, the engine will kinda shudder for a few seconds, almost as if it is burning the rest of the diesel out of the cylinders. Is this normal?

You assumed correctly, sir.

The shudder is due to the sudden stop of the heavy crank and rods. When the fuel is cut off, the high compression stops the engine very quickly.

Yep that shudder is normal...the Cummins in my tractor does the same thing.

i noticed the same thing. sometimes it shakes the whole truck.

That shaking is also most likely accompanied by a "chirp". What you are hearing is the serpentine belt continuing to spin for a half sec or so with the water pump, alternator etc etc.........after the high compression Cummins engine instantly stopped. It is completely normal. Every once in a while when mine shuts down it and it doesn't "chirp", I kinda miss it... [laugh]