TFL Truck tested them all towing 12,000# 5ers at a Ford press event. All 3 had 3.73 axles according to Ford. VIDEO Time to climb the 7% grade: Ford 2:36 Ram 2:45 Chevy 2:50
The article on Pickuptrucks.com mentions that there were sandbags in the beds of the trucks that were carrying lighter RVs to even the weight. They were at the same press event and did their own comparison.