How does the Duramax calculate loa?

[4x4 power]

I was wondering how the duramx calculates load? I know there isnt enough vaccum for a MAP sensor. I am assuming it is going to look at a number of sensor values but I dont know which ones please help me Thanks Joe

[Kennedy]

Primary input would be APP (pedal) but it can also use boost, mass air flow, etc.

Not sure what the underlying question is.