Hot Hot Hot

I have a 04 379 Pete with a 475hp bridge motor. The engine was rebuilt 240,000 miles ago, radiator last year. The problem is, when I pull a grade of 5 -6% the engine is getting hot. The water is up to 245-250%, however a bigger concern is the oil temperature. The high heat light does not come on but the oil warning light does and oil temperature is 210% oil pressure drops to 40psi from 70psi. I turn the fan on as I start to pull hoping to keep the temps. Down. I do not have a boost gauge so I'm not sure what it's pushing for boost. I can say that at 78,000lbs gross it will pull a 6% grade at 46mph. The exhaust temp is running around 950%. This has been this way since before the engine was rebuilt. Stacks are pretty black so I believe that fuel leaning is not the problem. Any thoughts on this.

 

I did the radiator and condenser cleaning. This engine has always run hot since I purchased it with 438,000 miles on it. It did blow a head gasket around 480,000 miles, had that repaired and at 523,000 miles it spun a rod bearing. So I spent 32 k and had it rebuilt. I assume that the aftercooler was replaced, but I'll check tomorrow and find out. As I said the water temp. Warning lights do not come on. Yet the oil pressure light does and the pressure drops. I am old school (44yrs experience) and pull grades where I can gain rpms if I give it more throttle, so I'm not lugging it. Generally I pull around 1,400rpms and can run up to 1,750rpms before it reaches peak torque and starts to fall off. Is there a way to check the aftercooler out to see if that's the problem before just throwing dollars out hoping that will fix it? If they did not replace it.