FWIW, I own 2 chevy trucks with the 6.5 turbo diesels in them. When you change water pumps the timing chain is exposed in them, and you can clearly see what condition it's in during the operation. I last changed the waterpump on one of the trucks in 2017. The engine is right around 265.000 miles at that time. The timing chain was nice and tight with no slop in it whatsoever. It is a roller timing chain and I was amazed at it's condition.
A diesel engine is infinitely tougher on timing components than a gas engine is because of the nature of a diesel engine the crank is always speeding up and slowing down just due to the design of an engine with 22 to 1 compression ratio. Watch the fan belt on a diesel at idle, and you can see the harmonics at work.
The 6.5 diesels will snap a crank in short order if the rubber in the harmonic balancer goes bad, they are known for this short coming if you don't catch the failure of the balancer right away, the crank will break. I don't have any idea of what material the roller chains in these engines are made from, but it's apparently a lot better design and material than we currently get for our Pontiac engines.
That said, the 195 4 cylinder Pontiac also had terrible harmonics, and Pontiac engineers used the link type chain that was a hybrid hardened link style chain that would last in that application, and also interchanged with the V8 Pontiac engines. I still own a 428 that I purchased the 4 cylinder chain from GM back in the late 70s when they were still available from GM. I haven't looked at it for decades, but it's still in the race car engine that is fully assembled that came out of the 69 GP stock car in my signature pictures. I'll have to tear into it at some time to see how it held up in a race application.
I'd really like to find out why the 6.5 diesel timing chains I mentioned have held up so well, and are a roller chain too...........
