Fan belt broke

[Ballerxl]

I didn’t check the ac pulley I’ll check that, and I haven’t checked if with the belt off it still makes the noise I didn’t think I was supposed to do that without damaging something, fuel has been changed out to the new style , and it does sound like the engine is knocking when at that rpm but I figured all Cummins engines sound like that.. and as I was thinking last night when I was driving home I was starting to feel a slight vibration coming in and out it would be smooth than a little vibration than smooth and little vibration and so on and than 40 miles later that’s when the belt broke and al that