The Cummins is doing the thing. I pushed it harder in Wyoming than ever before. Up till then, I was able to keep the EGT's below 1200 with relative ease, but that one 8700' pass kicked our butts. EGT ran to the mid-1300's and did not want to come down. I have the cooling fan RPM showing on the smarty tuner and it was on a whole bunch in that state in the wind. The cooling system is really good on these trucks, the temp runs at ~195 and when the fan is on full honk and the EGT is up, it stays at ~205. That fan is sized right.
I didn't catch the name of that pass but Ima gunna call it weshuda-duga-tunnel pass.
I guess it is called Sherman Hill. I don't need to go back there loaded.