Swapping the engines appears to be much more involved. The DT466 is a lot longer than the T444E. Requiring that the firewall be cut out and a doghouse into the cab. Plus the T444E only has 102K miles VS 303K on the DT466. Truck only sees about 4K a year so I don't think that the engine swap would be worth it. I am looking at the mileage benifit with the manual transmission.