WOW, how warm does a F 250 6.7 block heater get?

Its not just about having heat in the cab. A warm engine will produce less smoke so longer time between regens as well as less wear on engine at cold startup. Our Mercedes SUV had the supplemental heater as well and it was nice to have. That car didnt even have a block heater and had no issues starting even at 25 below, but a block heater would have helped.