Noise in top end of cummins isx

Ok, so my driver called last night and said the engine started losing power, and the oil pressure dropped to 20 lbs. He restarted it with me on the phone and he said it was making a rattling noise. Rode up to the truck and started it. It sounded fine, and oil pressure was back up to 35 lbs. No bottom end knock. (Rods, Mains, and oil pump) replaced about 50K miles ago. Revved it up a bit and there was a squeal and a rattle, sounded on the top end, and oil pressure bounced up and down. Shut it down and I guess Ill get it towed tomorrow. Any thoughts (wiped out cam bushings, cam)? The oil pressure going down to 20 lbs confuses me.

 

It’s a 8520 cpl. 2006. 640k miles on it. And I do have a weak number 3 injector.

 

Also it’s a CM870