Opinions on gear drive in BB

I will say this about gear drives.. If you have ever had a Mechanical 3406 caterpillar motor or any other big rig diesel apart then you would see they all have gear driven cams and injector pumps. Comparing apples and oranges here... but they are built for precision timing, durability, and longevity in mind. However they are designed to run at mostly max rpm of 2200 in most cases. I couldn't see a timing chain or belt lasting any amount of time in diesel applications.