The trick to re-using ARP head studs is to not strip them taking them out. I always manage to strip 1 or 2 taking them out. Allen (hex key) stuff and I don't get along at all. Perhaps I use too much locktite on the studs, but ever since I had one back out of the block, I am generous with the stuff.
Though if the motor is out of the truck, you shouldn't need to pull the studs out, just take the nuts off and pull the heads up over the studs.
If you have around ~200k or more miles on the truck, it would be prudent to replace the water pump. My stock one lasted 300k before I replaced it when I built the motor, but I just helped a friend replace theirs tonight with "only" 250k on the clock.
If the heads are off, you are at the point where installing basically any top-end upgrade is super easy. That would be a great time to upgrade your turbo, CP3, Y-bridge, injectors, up-pipes, or anything else you can think of on the top end. Should you? That's the question.
I'm with Arek: why is the motor coming out and the heads coming off? Think you cracked a piston? Basically, if we know why things are coming apart, we can better suggest what can/should be replaced in the process.
And if you're planning to just pop it open and look at it, be warned, basically none of the gaskets are reusable on the Duramax, so it will cost you around $500 just to pop the heads off and on again. I'm all for doing things for the experience, just know what you are getting into.
