The 453T is rated at 2500. If it has the new cross head pistons it could be rated at 2200. The 71 and 92 series were rated at 2100, but usually governed at 2300. Just as an example as to how times have changed, we now run our Cummins between 1200 and 1600 rpm. They are governed at 70 mph while turning 1450 in 10th gear and cosistently get 6 miles to the gallon where the old engines were lucky to get 4.