Killer Dowel Pin
No engine is perfect. The Cummins 6BT 12 valve diesel engine has one particular fault that is well known throughout the diesel community. And it's a cheap fix. One of the pins in the timing case has a tendency to fall out and wreak havoc with the timing gears and aluminum timing case. Buy a kit or make your own fix. It's very easy! Remove a bunch of stuff, take out one bolt, put a capture tab on it, dab on some red thread locker, reinstall the bolt, and you are good to go!