Not only did they use it form 1941-1954, but it will bolt up under a 37, 38, 39 and 40 with no problems and is a heavier unit than the 37, 38, 39 and 40 unit. In addition, that axle will take the car backing plates and hubs from 49 - 54, allowing you to use Bendix brakes on the front and five lug wheels. It is a nice conversion for a truck that gives you many "upgrades" for safety and looks.