Diesel Bombers - longest lasting Duramax

Hay people. I'm new to diesel bombers. Was wondering if somebody had aduramax with more miles then mine and stumbled across this. Decided I should sign up and let you know first hand what these diesels are capable of. To start my 04 gmc has the lb7 duramax. I got this truck from my grandpa when he bought a new one. He put a whole lot a miles on it. He bought it brand new and it has 750,000 km's on it now. After I got it it was running as good as new but soon after an injector failed which I know is common on the lb7. I was trying to decide if I should fix it or not because of the high mileage but decided what the hell. Install the new injector and see how long she goes. Since that job it's been running like a champ again. I had the dealer do the injector for me. Although I do most of the work on my trucks myself I decided to let the dealer do it cause I had the money at the time. The dealer said they had to pull the cylinder head off for some reason but they told me that the cylinders still had cross hatch in them. I was amazed by this cause I've rebuilt a lot of gas engines and the cross hatch in the cylinders are usually not visible by 50,000-70,000 km's. Anyways I asked the dealer if it would be worth it for me to put some money into it. All I want is the 5" mkm exhaust and a 4" lift with 33's. My grandpa drove it completely stock all those years. The dealer said well the cylinder are in extremely good shape but the bearings could be a different story. In the end they figured I could probably get another 250,000 out of her before she needs a major overhaul. So I'm gonna go ahead with the lift and exhaust. We'll see how long she lasts. The longest lasting diesel I've ever seen is a 6.2l naturally aspirated detroit diesel in a suburban. It still runs and has rolled over it's odometer. It has 1,600,000 km's with no major overhaul. Pretty amazing to me. Although I've seen some old cummins with major mileage on them that detroit takes the cake.